What Octane?

[Bantan]

Just curious to know, What Octane gas do you use in your VX?

[Cyrk]

93 for the Supercharger!!

[AlaskaVX]

92 is the highest octane at our pumps. In fact only Chevron carrys 92 so it's the only place I fill up, everywhere else is 90 premium.
Supercharged

[Dallas4u]

I'm supercharged, and I've been using 87 for a while... I just don't feel like buying premium every 270-280 miles!!!

I will, though, put in premium every once and a while... and will definitely go back if the price of gas drops at some point.

[Tone]

87 is what the book calls for. Supercharger recommends 91+ but our kncok sensor is able to handle the lower octane (with noticeably less power) without damage for those with the SC trying to save money...

[MZ-N10]

phew thought i was the only one getting 300ish miles on my vx....
________
The Sanctuary of Truth Pattaya (http://pattayaluxurycondos.com)

[Hotsauce]

I buy 93 octane. If thats whats actually dispencing or not is another story.

You can run with lower octane, but you increase knock count. Once knock count reaches some limit the ECU retards timing. It takes 4 degrees of retard to quench the knock of 1 degree too much timing.

More timing gives more power and mileage. Some of you have posted in the past that you get better mileage from resetting the ECU. This is reseting the timing table back to zero. You should not have to do this if you have enough octane to keep the knock sensor happy.

I'm guessing that you can go farther per dollar on the higher octane because of the increased timing.

It would be very hard to prove this without running several tankfuls of each gas through to get the ecu set to each gas. Resetting the ECU gives the lower quality gas a temporary mileage advantage.

John C.

[SPAZZ]

Use mostly 87...but when 85 is available my VX loves it...gets better mileage and performance

[AlaskaVX]

spazz:smack:

[VX_PA]

Just don't want to take any chances with lower octane fuel. It may seem to cost a lot, but it's still cheaper than throwing down another 5 grand for another motor. My VX is my hi-dollar ho. :cool:

[joe-yamma]

I notice better performance and slightly better using higher octan. I usually use 89, but I'm probably gonna start running 93 all the time.

Joe

[Navigator]

...For some reason I can't explain I keep buying 93 :naughty: Oh yeah, I get more GittyUp :D That's the ticket :yes:!

[powered by isuzu]

I see by the results of this survey that most of us can't afford high octane......what is up with the gas prices!!!! :mad:

[Bantan]

Originally posted by powered by isuzu
I see by the results of this survey that most of us can't afford high octane......what is up with the gas prices!!!! :mad:

Actually Guys, the reason I started this thread is becauce the service manager at my Isuzu Dealer told me recently to stop using 93 octane. He also switched my VX from synthetic oil (which I've used from my first oil change). I believe his exact words were " this engine wasn't built for 93 octane gas or synthetic oil, it will run smoother and better with 87 and regular oil".
Is this BS?

[VX_PA]

High octane gas and synthetic oil will not hurt your engine. However, 87 octane gas and regular oil will not hurt your engine either. It was designed for 87 gas and regular oil, but better gas and oil are better for your engine. There are plenty of tests and written facts to back up my statement. Can your mechanic provide in writing tests that back up his statement?? Until he can, he's full of BS. Anyone else??

[Tiger66]

BS on both! with the SC you can certainly use the higher octane, if it doesn't need it, it will be just wasted but no harm. And synthetic oil meets and/or exceeds all SAE specs. Plus it does not breakdown like conventional oil. The guys does not know what he's talking about.

[VXRaNgEr]

Where to they FIND these service guys!? An octane rating is just how resistant a fuel is to compression detonation (you want the spark to ignite the fuel, not compression or else you get knocking). Higher octane is just more resistant to causing knocking. Ain't NOTHIN wrong with that. Usually, the higher the compression ratio, the higher the octane, but if you put higher octane in your engine its only going to run better and protect it better from pre-detonation/knocking. Now go back there and kick him square in the huevos!

BTW...because of our elevation, Colorado's regular grade is 85.

[SGT.BATGUANO]

He may not be totally wrong on the octane thing. I read somewhere that higher octane gas doesn't "burn" as efficiently in an engine that doesn't "need" it. What you need is a method to monitor your knock counts and up the octane until they stay at zero.

[redline]

Neighbor owns a gas station /He says Mid grade is the way to go.Has all the additives to keep injectors clean and octane is 89 .Can't tell the difference w/Premium 94 octane ,just a lighter wallet.:flame2:

[AlaskaVX]

Originally posted by VXRaNgEr
BTW...because of our elevation, Colorado's regular grade is 85.

Thats crazy, it actually says 87 is the minimum for the VX in the manual. I have never heard of anything less than 87 :confused:

[AK VX Lvr]

Usually use 90---since it's the highest available everywhere. I spoil my VX even if it does lighten the wallet (maybe needlessly).
:yes:

[VXRaNgEr]

Hmmm....it appears you're right:

http://www.koaa.com/features/investigates/view.asp?ID=251

Looks like I'll be switching to 87!

[AlaskaVX]

If I was in Colorado I would start getting people together and get the "public outcry" that they say they need. As it is now up in AK we pay $1.63 for regular 87 octane, if you are paying more I would be :mad:! I really can't see how everyone would be OK with this :confused:;eeky;
And I thought Spazz was just messing around saying 85, especially when he stated he got better performance out of it ;eekr;

[Chopper]

I've used 93 and Mobile1 since it was 11mi. old.Still purrs just fine thank you

[Newsman]

Hotsauce -- you and I were thinking the same thing...

I've actually run my VX (stock engine) through a test of 10 tankfuls of 87 and 10 tankfuls of 93. I do about 50% city driving and 50% highway (with offroading another 10% -- wait a minute...) and I found that my gas mileage did go up slightly with the higher octane (something along the order of about .5 mpg).

My main goal in the test was to see if the higher octane was actually cheaper to run (to see if the better gas mileage would compensate for the higher price at the pump) and I found it really didn't.

If I remember correctly when I did the test it worked out to about $.08 per mile on the 87 and about $.10 per mile on the 93.

In terms of performance, I honestly haven't seen any performance dip or higher knock count on the 87.

[VX-KING]

Sorry guys but i mix my gas for my vehicross

[VX_PA]

Originally posted by VX-KING
Sorry guys but i mix my gas for my vehicross

Mix it?? What are you running??

Octane Boost (104+)
Turbo Blue
Jet Fuel
50/50 Mix

Wow, that's some machine!!!
;eekp;

[Dallas4u]

Originally posted by VX-KING
Sorry guys but i mix my gas for my vehicross

Don't be sorry. many people mix different octanes to get a good "in between" for the money.

[Tone]

VX King - the only one to talk so much about a VX NO one has ever seen....

[VX-KING]

Tone VX King - the only one to talk so much about a VX NO one has ever seen....

Seen..... (What)

[crager34]

Maybe I need a couple tanks to do this, but ran the HIGH stuff for a tank and got around 260 miles. Than ran the low stuff and got 250 miles. First thing I am hoping that I am getting the standard miles out of my VX - The second is... the price isn't worth ten miles and I didn't notice any performance issues.

[VXRaNgEr]

260 miles / 22.5 gallons = 11.6 mpg

Ouch. That's assuming you run to tank to bone dry though.

[Dallas4u]

RIGHT... meaning that, by the time you fillup (before bone dry), you actually receive less mpg.

By the way, I usually get between 260 - 280 miles per tank.

[ctp]

My average for the 1500 mile drive fom Texas was 19.979mpg. I started with a full tank, finished with a full tank and divided the miles by the gallons I got on the way. It seemed a little easier than running the tank dry:D

[Reg Hinnant]

here's something to try........
Read this http://www.rxp.com/Octane.htm
then this http://www.rxp.com/FAQs.htm
Dyno results http://www.rxp.com/test-cov.htm http://www.rxp.com/6.htm

Snake oil? Try a bottle and you tell me. :confused:

[Dallas4u]

Hmmm... why not. I may just pick some up after work tonight and try it. Hell, I did throw a toulene mixture in my tank a while back... can't be as nervous with this stuff as I was doing that!

[xdfarrx]

I read that due to atmospheric conditions above 4000 ft. octane above 87 is a waste as the conditions don't support the combustion to have any benefit. I read this a year ago in Petersen's offoad mag. At sea level the benefits are tangible apparently. I do as I read and here at sea level I rock as high octane as I can. An earlier thread suggested when the timing does have to be advanced by the ecu the car can get better fuel econ, which I was also told by a friend who worked in CART-

[xdfarrx]

Ooops I meant to say above 87 is a waste-

[WyrreJ]

That may be true, I haven't tried to think the physics through to check. But, it probably isn't true for cars with turbos or superchargers since they work by increasing pressure beyond the ambient air pressure, so sea-level or 9,ooo ft up, the pressure in the engine with a supercharger ought to be about the same.

[Chopper]

super chargers were made popular on WW2 aircraft to allow engines to operate at greater altitudes by compressing the thinner air to supply the o2 to allow operation at those altitudes. A supercharger at sealevel is vastly different than a supercharger at 9000 or 10000 ft. . Same for turbo... only diff is, belt or gas driven.

[Jolly Roger VX'er]

I run 87 octane and Mobil 1 SuperSyn Oil. First time in my life that low octane seems to perform well. All of my other previous rides either specified higher octane (Turbo) or simply "pinged" when it wasn't used. As for miles per tank...I haven't been able to break 300 miles on a tankful yet! usually around 260.

[Triathlete]

87 since I've owned it! Especially now that gas just went up 30 cents a gallon in the last 4 days here....OUCH!

[crager34]

Since my first post, I thought I would run a few tanks on various grades. Seem to be getting a little better mileage with the mid grade...I think it's 89 here in Columbus, OH. Better by about 10-20 miles is all.

[VehiP&J]

My wife and I just got our vx only used mid 89 octane in it. Actually nice we are used to only being able to use high octane 93 gas.

[WyrreJ]

Originally posted by crager34
Seem to be getting a little better mileage with the mid grade...I think it's 89 here in Columbus, OH. Better by about 10-20 miles is all.

FWIW, it is usually cheaper to buy 87 and 93 in proportion and let your gas tank mix them up to 89. In fact, that is usually what the gas station does at the pump anyway, they don't have a tank for 89.

[kpaske]

I've been using 87 since I bought my VX back in '99 and never had any issues until recently. At about 75K miles, I noticed it was starting to ping, so I switched to 89 octane and it seems to be running smoother and performs a little better. Can anyone explain what may have caused the change?

[Reg Hinnant]

kpaske
Carbon build up?

[kpaske]

Possibly; how do I go about cleaning it out? On my last vehicle, I just removed the intake and sprayed some carb cleaner around and it seemed to help a bit. Can I do the same with the VX?

I just cleaned and oiled my Calmini air filter and upgraded to some Bosch Platinum +2 plugs and it seems to be running a lot smoother; but I'm still using 89 octane.

[Dylan19]

91 Octane here in Utah, thats usually the best I can find. I have enough miles that i like to spoil her a little.

[ScottinMA]

Seems to be a lot of supercharged VXs running on 87 which John (Featherfoot) strongly advised against. hmmm..low octane detonation issues are resolved by that computer?


Scott

[SpaceTruck'n]

"Actually Guys, the reason I started this thread is becauce the service manager at my Isuzu Dealer told me recently to stop using 93 octane. He also switched my VX from synthetic oil (which I've used from my first oil change). I believe his exact words were " this engine wasn't built for 93 octane gas or synthetic oil, it will run smoother and better with 87 and regular oil".
Is this BS?"


Your service manager is a wanker.
Synths are fabricated, (not refined) for the maximum lubrication of ALL internal combustion engines. With hydrocarcabons that are... Whatever. Its a long story and it's gettiing late.
Early synthetic oils tended to suck. But then again early engines tended to suck.
That was then, this is now, synthetic oils and and engines are times better. Even gas tubines can benifit from the wholesome creamy goodness of synthetic oils.
Mobil 1 syth is now the finest motor oil INVENTED.
Air Force One uses Mobil 1.
As far as octane...

Do what you feel man, but I'm not hip to $2.00 a gallon. But that's my view I could be wrong.

[Bantan]

Originally posted by SpaceTruck'n
Your service manager is a wanker.
Synths are fabricated, (not refined) for the maximum lubrication of ALL internal combustion engines. With hydrocarcabons that are... Whatever. Its a long story and it's gettiing late.
Early synthetic oils tended to suck. But then again early engines tended to suck.
That was then, this is now, synthetic oils and and engines are times better. Even gas tubines can benifit from the wholesome creamy goodness of synthetic oils.
Mobil 1 syth is now the finest motor oil INVENTED.
Air Force One uses Mobil 1.
As far as octane...

Do what you feel man, but I'm not hip to $2.00 a gallon. But that's my view I could be wrong.

Thanks, I was begining to think so about this guy anyway, if you can't trust the Dealership you bought the thing from, who can you trust.:madp2:

[AlaskaVX]

Originally posted by Bantan
if you can't trust the Dealership you bought the thing from, who can you trust.:madp2:
US! :biggroup:

[Bantan]

Originally posted by AlaskaVX
US! :biggroup:

True that! ;Dp;

[OZ VX]

I'm in Australia and 87 octane seems a bit poor, I would never go that low.

Our Standard Octane Rating for Regular Unleaded is 91, and we have a middle grade of 95 and Premium is 98 octane. I own a non turbo Supra as well as a VX and I always use 98 octane (shell optimax) in both cars, another good premium we have is BP Ultimate.

I have found a big difference in power and economy, and the engine seems to run a lot better too. It may be dearer at the pump but you will also get more range out of your tank.

My advice would be to always use the higher octane.

[MrCrowley]

hey OZ- your octane ratings are a little different than ours. I dont remember all the specifics, but being a Subaru STI and WRC fanatic also, I read alot of their forums. Since the STI is a high compression, high boost car, all those guys have danced around back and forth to figure out why everybodys info about octane internationally is different. It all comes down to the math used to determine octane ratings in different places. I remember the US and Europe are different, but cant remember if you guys use European ratings or if you upside downers have your own!


;Dy;

[Tone]

SCed VXs should be running a MINUMUM of 91 octane - run lower and step into it a lot and the computer cannot compensate for it and will soon destroy the engine through probable piston burnthrough. ?_The U.S. uses the following formula: Road Octane Number = (RON + MON)/2 It is a common practice in many European countries to advertise the Research Octane Number on their pumps, so you may see unexpectedly high octane values when travelling abroad.

Unless SCed, use the 87 Octane the owners manual recommends. One - and a very important - exception is that when a vehicle gets older, the normal build-up of fuel- and lubricant-related deposits in the engine can increase the fuel octane number a car requires to prevent engine knock. For this reason, if a car more than a couple of years old experiences engine knocking, the problem may be solved simply by moving to the gasoline with the next-higher anti-knock index.


Following is a great article on selecting the best gasoline for your needs

By: Phil Coconis/autoMedia.com
Many people pick a gas station based on price and/or convenience, probably because they feel that most brands of fuel are pretty much alike. Is that really the case, though? Since your choice of gasoline directly affects engine performance, economy and longevity, along with the environment, it pays to know the facts about different types of fuel.

RON, MON
Let's start with some basic information about octane rating. The term octane is a familiar one and it's important to follow the recommendation that your vehicle's manufacturer specifies in the owner's manual. That number is actually an average of two different octane numbers (Motor Octane, or MON, and Research Octane, RON). These refer to the fuel's ability to resist "knock" (fuel igniting before the ignition spark and resulting in a "flame front") under different driving conditions. MON affects knock at high engine speeds or loads, RON at low ones.
What do these two types of octane measurements have to do with fuel selection? Well, if your engine knocks or pings under only one of these conditions, changing to a different brand of fuel may solve the problem. But if knock occurs under both conditions, then there's likely a mechanical problem that needs attention. It should not be necessary to use a fuel of a higher octane rating, unless all other remedies have been tried.

Fuel Myths
We should address a common myth about octane. Know that using fuel of an octane rating higher than that of the manufacturer's recommendation will not increase performance, fuel economy, lower exhaust emissions or increase engine/fuel system life. Usually, only vehicles with high performance engines (fitted with multi-valve heads and/or a supercharger) require a higher-octane fuel.
Does this fact about octane mean that "gasoline is gasoline" and they're all made according to the same formula? Should you just go for the bargain du jour and pocket the difference? Actually, oil companies are competing with each other, and that means that they don't share formulas with each other, nor do they necessarily get their crude oil from the same place. That means the final product will vary, from brand to brand and grade to grade. (And there's even some slight variation within brands, as gas is reformulated both seasonally and geographically, but that's another story.) You do truly get what you pay for—but is it worth it to you?

Price & Grade
Let's examine some of the differences in price and grade. The first is in the quality of the crude oil used. Cheaper grades have more undesirable compounds, such as sulfur, olefins, and diolefins, which cost the refiner to remove. The more of them removed, the higher the price. Since these compounds contribute to higher exhaust emissions, reduced service life of catalytic converters and sludge/varnish buildup in fuel delivery/intake systems, those who plan to keep their vehicles for many years would wisely opt for the better quality gasoline. One easy tip-off that marginal-quality gasoline is being used is a foul sulfur smell emanating from your exhaust (assuming there's no engine malfunction).
Besides having more of the aforementioned compounds removed from them, higher quality fuel also includes more energy enhancing and fuel system cleaning (detergent) additives. These can yield better fuel economy and performance, plus result in reduced maintenance costs. Reformulated Gasoline (RFG), sold in many states and in most urban areas, has also added to the cost and complexity of modern gasoline refining. Although refined under tight government guidelines, there are a variety of formulas, with varying results in terms of cost and performance, with the better performing formulas generally costing more. RFG, deemed necessary to reduce exhaust emissions, differs from earlier gasoline formulas by having more aromatics removed, such as benzene, sulfur, and olefins, as well as the addition of compounds called oxygenates (which raise the oxygen content in gasoline, thereby reducing CO emissions). There are two popular oxygenates used presently—MTBE and Ethanol.

Oxygenates
MTBE (methyl tertiary butyl ether), produced as a result of reacting methanol with isobutylene, is the more stable (less volatile, or prone to evaporation) of the two, and yields a greater octane increase. It tends to produce fewer driveability complaints, and is friendlier to older-car fuel systems. It can be blended, under present rules, at up to 15 percent concentration levels. It is also the more controversial of the two, as it has a higher level of toxicity (not necessarily more toxic than the gasoline it's blended with, though).
Ethanol is produced from fermented grain or corn. Yep, distilled from mash! It's not any more toxic than hard liquor and can be blended at up to 10 percent concentration levels. In Brazil, many vehicles with some modifications to fuel delivery systems run exclusively on the stuff! For environmental reasons, this is the more politically correct of the two oxygenates.
On more modern vehicles with electronic fuel injection, RFG poses no real problem (except for a slight drop in fuel economy), but owners of vehicles with carburetor engines may notice driveability problems under some conditions, due to the effectively "leaner" working fuel mixture. Carburetor modifications, if done skillfully, can solve this problem.
So what's the bottom line? Don't pay extra for a higher octane, unless your owner's manual specifies it or you've modified your engine for higher horsepower. When it comes to choosing between brands of gasoline, however, you may find that paying a bit more at the pump has a definite impact on performance.

© Copyright 2004 autoMedia.com Inc. All Rights Reserved.

[thebear54]

Use 89 regularly but will spluge every fouth tank full to a 93 to keep the injectors cleaned out:)
John

[thedutchguy]

Here in the Netherlands there's only 95 and 98 at the pumps, o yeah Shell sells Vpower fuel (that's 100!)

[Tone]

Higher octane does NOT clean injectors...

[kpaske]

Well, I'm back to using 87 regularly again. It seems to ping a bit more in the mid RPM's, but I get better gas mileage. Don't know why, but upping the octane to 89 lowers my gas mileage, so as per Tone's suggestion, I'm going to try some different brands to find an 87 that plays well with my VX. Does anyone have any brand preferences? (I usually use the cheapest I can find ;eekb; )

BTW, how often do fuel injectors need to be cleaned? Is that something we can do ourselves or does it require special equipment?

[kinnaq]

I use "super" premium, it is...90 octane! :rolleyes: It's funny how the prices kept going up for gas as the octane went down.

[circmand]

not VX specific using gas with octane above revomended will do nether harm norimprovement. Using oil rather than recomended can cause engine failure. That being said I occasionally run 110 octane through me Jensen Healey and clean the carbs out.

[vt_maverick]

Hail circmand, ancient thread archaeologist. :D

[circmand]

Hail circmand, ancient thread archaeologist. :D

Hey I dont read the post dates. If it pops up in the unread posts area I read it. I do wonder why these posts pop up. I think it is due to having a poll attached to it and when someone votes it pops up as unread.

[vt_maverick]

You are correct. Very annoying "feature."

[crager34]

Since my last post here I bought another VX (first was totaled) and my gas mileage has been better. I use mid grade and consistanly get 16 - 17 MPG.

However, lately my MPG's have went down to around 13 and I am not a heavy foot driver. Time for a fuel pump replacement I guess. Gonna try the low grade fuel too.

[Mile High VX]

Since my last post here I bought another VX (first was totaled) and my gas mileage has been better. I use mid grade and consistanly get 16 - 17 MPG.

However, lately my MPG's have went down to around 13 and I am not a heavy foot driver. Time for a fuel pump replacement I guess. Gonna try the low grade fuel too.

Depending on how long you've had the new one...winter gas will typically yield lower MPG than summer gas...don't overreact to reduced mileage in the winter.

[mindaugas]

91, I think that's the highest Colorado goes. I've always put premium in everything I own, it amounts to a few dollars more. Usually $.20 cheaper, lower octane would be $61 if you filled the whole 22 gallons. It's $66 for premium at $3 a gallon. I think those are going rates, honestly I don't even look at prices anymore, it just makes me sad.

And now I'm going from a 99 Subaru Legacy that cost $30 at the most to fill and got 25mpg to this VX. Although I put 200 miles on a full tank of gas and I'm half way down. So 400 miles to a tank won't be bad, but I have a sneaking suspicion I won't get that. I will be doing mostly highway driving to and from work, but it's into downtown Denver via I-25, I'm not sure if you can count that as highway driving during rush hour.

[BeeVenom]

I'm doin' the 93 stuff with the S/C. Tank is small too, so it doesn't hurt that bad! :o

[vt_maverick]

22 gallons is small? What's your other truck, an Excursion? ;)

[mindaugas]

22 gallons is small? What's your other truck, an Excursion? ;)
lol, right? I was surprised when I hit $50 in this little thing, my 4 door dakota had the same size tank I think, but didn't get much better mileage despite 2x4

[Hiredgoon]

I was curious about this so I actually experimented with regular vs. premium. I ran spreadsheets (I know, pretty geeky) to calculate my gas mileage based on what octane I was using and where I was buying it, in case that had an impact. Based on almost two years of testing, I'm getting 2-3 MPG higher when I use the 87 octane fuel as opposed to the 91 (or 93 in a couple of cases). I don't notice any appreciable difference in the sound of the engine or the amount of power I'm receiving, but since that's all subjective and the only thing I am actually measuring with any sort of rigour is mileage, I can't say for certain.

I do know that I am running a completely stock engine.

[mindaugas]

That's really interesting, and good testing. I wonder if it has any more wear on the motor than 91. Isuzu recommends 87, so I'm guessing not. I just really want to make this car last for a really long time, so I'll try anything that will lengthen life.

[Mile High VX]

I was curious about this so I actually experimented with regular vs. premium. I ran spreadsheets (I know, pretty geeky)

You sir, are uber cool...:smilewink:bgwo::bgwb::bwgy:

[VX KAT]

I was curious about this so I actually experimented with regular vs. premium. I ran spreadsheets (I know, pretty geeky) to calculate my gas mileage based on what octane I was using and where I was buying it, in case that had an impact. Based on almost two years of testing, I'm getting 2-3 MPG higher when I use the 87 octane fuel as opposed to the 91 (or 93 in a couple of cases). I don't notice any appreciable difference in the sound of the engine or the amount of power I'm receiving, but since that's all subjective and the only thing I am actually measuring with any sort of rigour is mileage, I can't say for certain.

I do know that I am running a completely stock engine.

Great data! Any winter blend vs. summer blend data or impressions, or did you do just an overall annual average? Probably hard to determine exactly when the blend changes anyway (although seems like I've seen stickers on the pump when it's the winter mix??)

[circmand]

Great data! Any winter blend vs. summer blend data or impressions, or did you do just an overall annual average? Probably hard to determine exactly when the blend changes anyway (although seems like I've seen stickers on the pump when it's the winter mix??)

Its not like the stations use different tanks or change over at the same time. Basically the refineries change over thn the tankers pick up the new fuel and just fill up the tanks with the old fuel and it mixes

[Luna X]

with prices the way they are..... good 'ol 87 sounds just right to me... ;)

[BeeVenom]

I'm only run 93 octane, but that's cuz of my Super Charger being there. I'm averaging about 19 (+)(-) at fillups. Thought a couple years ago that I was surpassing 21+ highway but my calculator must have been haywire back then! Mileage is pretty consistent and speed does make a difference (ie: 55 vs 60 vs 65 vs 70). Run BP premium all the time and get their 5% rebate which helps make it feel a little better. Not much, but a little better!

[H3_VX]

Just to poke my nose into this thread, is it true if you use synthetic oil and then switch back to regular it could damage the motor?

[89Vette]

Just to poke my nose into this thread, is it true if you use synthetic oil and then switch back to regular it could damage the motor?

Only on Sundays when the white Rhino charges his Visa card.

:disturbed

[evillecutter]

93 (or 92 at some stations) octane - 300 miles to a tank - ive never driven to where the gas light has come on but ive noticed that when my gas gauge reads half a tank i can only put about 9 gallons in it until it is completely full -so im thinking if i have a 22 gallon tank when im on empty i could actually still have a few gallons left in there - and with the difference between an entire tank of 89 vs 93 being less than $5.00 id rather just run the cleaner stuff just to be safe

--funny (sad) how in 04 people in this thread were complaining about $1.84 a gallon

[VX KAT]

93 (or 92 at some stations) octane - 300 miles to a tank - ive never driven to where the gas light has come on but ive noticed that when my gas gauge reads half a tank i can only put about 9 gallons in it until it is completely full -so im thinking if i have a 22 gallon tank when im on empty i could actually still have a few gallons left in there - and with the difference between an entire tank of 89 vs 93 being less than $5.00 id rather just run the cleaner stuff just to be safe

--funny (sad) how in 04 people in this thread were complaining about $1.84 a gallon


My tank runs that way also....apparently more gallons fit in the first half of the tank (:laugho:)....
oh, and it's capacity is 22.5 gallons....cuz ya know that extra half gallon can getcha a few more miles ;)


I've gone as low as the needle can go, (but no light) and total fill was only 18.80 gallons.:_confused and 297 total miles.....
I've never hit a 300+ miles tank yet....cuz I think it's really close to empty and don't want to run out....but it appears I've got about 50+ miles left (3.7 gallons @ 15 MPG).

But living out in the boonies, and often driving off road in the boonies...that hidden 3 gallons is a great safety cushion.


OCTANE- several past discussions about Octane vs. MPG.
Some say higher octane gets higher MPG.
Someone ran a real detailed experiment on this. Can't recall who...(maybe HiredGoon??)
Think they found higher Octane (Premium) DID increase MPG a bit.

I tried it...3-4 months Premium vs. many months regular....not much difference in MPG that I could see.

[evillecutter]

i didnt get all the way empty but i get almost exactly 75 miles per quarter tank -i just changed the fuel filter too maybe that could help mpg? thought it couldn't hurt because the old one looked like it hadnt been changed in a long, long time - and ive never really heard anything about higher octane gas getting better milage, but i have shortly researched how they make the different grades and unless we are being lied to (wouldn't doubt it) the higher octane is supposed to leave less gunk in your engine i.e. burn cleaner because it has less impurities in it - but either way i didnt buy it to save on gas :) - its worth it

[VX KAT]

but either way i didnt buy it to save on gas :) - its worth it

:thumbup:
Ain't that da truth!! Fun is more enjoyable than MPG to me... :thumbup:

[89Vette]

OCTANE- several past discussions about Octane vs. MPG. Some say higher octane gets higher MPG.


Even within this thread, you'll find others who said the opposite...that lower octane produces best power by not inhibiting the "burn". Unless someone has run scans and sees evidence of timing retard, I gotta think 87 is best -- like the owner's manual states.

They wouldn't have coded timing tables for 93 octane and said use 87. Every few months you see how people are wasting their money buying "high-test" thinking it's better for their car. If it doesn't require it, it's not better.

btw...my guage hangs on full until 40-50miles, then it drops like a rock to 1/4 tank. So, it takes 50m to get down to full...and 25 miles to drop the next 1/4 tank. Pretty nice calibration their Isuzu techs!

Yeah...I finally broke my personal best and hit 16.5mpg last week. I finally got a few miles/day on the hwy. But, it's not the best cause it's during the to/from rush hour.

[RickOKC]

I always use 87 octane and my mileage is all over the place. I was really worried after one road trip when the VX was about 4 MPG lower than usual. The next day I took a shorter highway trip and it was suddenly 2 MPG higher than average. On the way back it was 2 MPG lower than average. Now I keep an eye on wind speed and direction - apparently it makes quite a bit of difference!

[ALC1717]

You Guys that claim you get over 300 Miles per Tank is hard to believe unless that is strictly Highway Driving ONLY ! There is NO Way the VX gets 300 Miles per 22 Gallon Tank driving Locally and if you guys claim it does with all due respect you are all " Full of Crap " ! My VX runs fine with Regular Gas and Oil, that is what ISUZU recommends.

[evillecutter]

You Guys that claim you get over 300 Miles per Tank is hard to believe unless that is strictly Highway Driving ONLY ! There is NO Way the VX gets 300 Miles per 22 Gallon Tank driving Locally and if you guys claim it does with all due respect you are all " Full of Crap " ! My VX runs fine with Regular Gas and Oil, that is what ISUZU recommends.

i was one who claimed that... i and spoke too soon (sorry didnt mean to lie) - i did go from full to 3/4 tank getting 70 miles a few times but that does not happen very often and def doesnt happen on any other part of the fuel guage - i would say 240 is much more accurate for me and i have done everything i can think of to improve the fuel efficiency (i also have no suspension mods and ride stock sized high performance street tires)

[circmand]

Very slow on 1st quarter of tank then you can see the needle moving. Mixed terrain but all pavement and depending on the lights you can get better MPG. I once got almost a 100 miles on the 1st quarter tank but finished at 280 for the tank. The light had just come on so i say 300 is just possible if you are mostly flat or downhill

[89Vette]

Of course, 300 miles from a tank is possible. 22gal x 15mpg = 330miles -- if you ran it bone dry. With your typical 2 gals left, you're sitting right at 300 miles. For me, that's mostly city driving as I get right at 15mpg city.

On the opposite end, 19mpg would net 418 miles from a tank. If you jumped in, got on the hwy, and ran from a higher elevation to a lower elevation -- hwy only -- I bet it could be done. You'd probably have to stick with 60mph or just barely above that.

A strong tail wind could give you the same result.

I've seen a couple post 400 miles in a tank (in earlier years) but you have to remember 100% gasoline provides better results than that cheap-azz E10 they're ramming down our throats. (Plus, in the earlier days of the forum, the units had lower miles and were in better shape [on the average])

Because of the way the VX tank reads, it's hard to believe people run it empty enough to hit 400 miles anymore. Same goes true for 300 in the city. But, it's certainly possible.

If you're not getting close, pump your tires up to 35psi and make sure everything is tuned up (including clean injectors). You can get it.

(Caviat: high elevations)

[Cobrajet]

I just came back from a trip from Northern Virginia to Nashville where I kept very good records of mileage because of this thread. I drove a total of 1321 miles (mileage corrected based on GPS), using 69.2 gallons, getting an average 19.1 MPG. I would say this was 95% highways miles, and probably 70% at 75mph. (I generally ran at 5-over posted speed.) First tank (ALL highway) I got 379 miles on 19.8 gals, with the low light on the last 4~5 miles. Tank two (a few local and stop-and-go miles) I got 381 miles on 20.1 gals, again with the low fuel light on for the last few miles. The next tank was all highway, and I played it safe filling after only 353 miles, 19.1 gals. The last fill was only a partial fill after 183.7 miles, 10.2 gals.

I generally do not get over 300 miles on a tank because I no longer make long commutes, but lots of short trips over the course of weeks between refills, which is the worst case scenario. It was nice to see that my VX is still capable of getting 19+ mpg on the highway. I have a few more trips planned for this year, so I won't need to rent a car to save money!

And to keep on topic - ALL regular unleaded! My VX has never seen premium, and never will! :yesy:

[89Vette]

I just came back from a trip from Northern Virginia to Nashville where I kept very good records of mileage because of this thread. I drove a total of 1321 miles (mileage corrected based on GPS), using 69.2 gallons, getting an average 19.1 MPG. I would say this was 95% highways miles, and probably 70% at 75mph. (I generally ran at 5-over posted speed.) First tank (ALL highway) I got 379 miles on 19.8 gals, with the low light on the last 4~5 miles. Tank two (a few local and stop-and-go miles) I got 381 miles on 20.1 gals, again with the low fuel light on for the last few miles. The next tank was all highway, and I played it safe filling after only 353 miles, 19.1 gals. The last fill was only a partial fill after 183.7 miles, 10.2 gals.

I generally do not get over 300 miles on a tank because I no longer make long commutes, but lots of short trips over the course of weeks between refills, which is the worst case scenario. It was nice to see that my VX is still capable of getting 19+ mpg on the highway. I have a few more trips planned for this year, so I won't need to rent a car to save money!

And to keep on topic - ALL regular unleaded! My VX has never seen premium, and never will! :yesy:

Very nice and thought out! I love the detail provided -- and comparison between city/hwy! Glad to hear you can get 19mpg!

Nice job, Gregg!
Gregg <LOL>

<cheers!>

[antdag22]

Just drove from FL to NJ. 22mpg all the way. 99 black, mobil one 10w30 and filter, 35psi factory 16s, 93 octane. Checked 3 times.

[VXobsession]

I used 87 when I first got my VX but tried 93 once and never went back. Much more power and idles super smoother. Oh, and my highest mileage was about 320. It's my daily driver but I occasionally drive an Intrepid about once every couple of weeks...it'd be nice if I could remember to use 87 in my CAR instead of involuntarily hitting 93 out of habit from driving the VX so much.

[44ficus44]

I just get whatever mexico sells.... kinda stuck with one down here. the other one is just full of lead.... must say.. my VX prob hates it

[SinJin]

My best MPG is 17.2.

That's nearly all freeway driving @ 65mph+.

I run 87 Octane.
No mods on the VX.
My engine has 145K on it now.
I use 5w 30 Royal Purple oil and it's changed within every 5K miles max. As often as 3K.
I ran Michelin summer tires (Latitude Sport IIRC) @ 35psi during my MPG checks.
Air Filter was new during the MPG checks.
No tune-ups in the past 50K.

*EDIT : Also, I only drive using the Power Drive selector.

[RedBlur]

I was just wondering what type of gas mileage people were getting during my road trip yesterday. I ended up at 19.3 MPG using Shell 87 gasoline, although I was probably closer to the 20MPG range before I sped up from 70 to 75MPH. That was about 90% highway miles. I'm lifted and have oversized tires, so that isn't helping my mileage any. I'm also throwing an EGR code, but I tend to ignore most EGR codes I get unless the engine doesn't seem to be performing well.

I thought that was pretty good considering that my VX was sitting for the better part of 3 years, although I did help it out a bit with a fresh oil change and injector cleaner. Definitely better than the ~8 MPG I got for the first few miles I had it on the road... I probably needed to get through the old gas.

I bought a gauge a while back that hooks up to the OBDII port to monitor MPG as well as other vitals. I need to calibrate it because the gas consumption numbers aren't super accurate (seems to be about 5-7% low), but it is nice to use as a comparison and to monitor driving habits. Maybe I'll throw some 89 or 93 in it on my way back and see how it compares.

[vp277]

There are more efficient newer vehicles out there, I think what counts with the VX is fun per gallon and the fact that you're driving a unique vehicle. Lousy mpg is a small price to pay...

[Leon R]

I am staying at consistent 14mpg (about 80% highway commute). But my coolant temps are almost always around 160*. So am pretty sure that my thermostat is stuck partially open. Only if it wasn't such a PITA to replace it :(.

[vp277]

Running cold is bad for the fuel economy and bad for the engine, change that thermostat. Test a replacement in a pot of boiling water to make sure that it opens correctly. Also, according to some posts here the "Power drive" option improves the mpg a little.

[magellan]

Some interesting replies here - i guess most of you all run the 3.5 where as here in Australia we run the 3.2, and going on 300mi = 482.80km i get an average with hwy driving of 520km in winter and 500km in summer - AC doesn't make that much difference really. I use Caltex Vortex Premium 98 and do notice a difference if i run 95 or 91. 20 inch rims help to i believe.

[EVO]

I ran E85 half tank twice (E85 is equivelant to 105oct) and there is a noticeable difference!! E85 did trigger the check engine light after the second tank though! Horrible gas mileage running it, I got around 12mpg. But it ran better with it in the tank! Have gone back to 87oct. and the check engine light has gone away. I think I'll make it a bi-monthly treat!!

[VXCanada]

I typically get 330 miles per tank 530 km as per the GPS log (summer time). Using around 75-77 liters on a fill up typically (19.8-20.3 US Gallons). I'm on 31.5" tires (285/60r18 Geolander AT-S).

This translates to about 14.5 L/100km or 16.22 MPG (US). It's around 75% hwy, 25% city normal driving with "occasional" heavy footed acceleration.

I use 89 Gas.

T.

[Hades]

I get crap mileage, making me think its running in limp mode or something. Like 10 mpg around town and 17 highway. Granted the 10 mpg is usually trips less than 5 miles, but does suck having to refill every 150 miles. 87 only, fuel gets boated in up here and is almost always over 4 bucks a gallon unless you go to costco or the company that barges it in.

[circmand]

EGR valve, replace your pcv valve those 2 steps got me another 100 miles a tank