Sudden Drop In Mpg

[DK]

I had my 30,000 mile service at Sierra just before Christmas -- replace PCV valve, lub, oil, diffs, trans, TOD, etc. -- and since I got the car back the MPG has gone from an average of 16 to 13.

The car is not running rough, no smoke or strange noises, idle okay. Any idea what could have been resete, disturbed, left undone or ? that would cause this drop in milage?

Thanks.

[thedutchguy]

Maybe they replaced your new air filter with an old one?

[Joe_Black]

dutchguy has a point in that it may be a more restrictive air filter than what you had before. Also, be sure to check your tire pressure as you may have been running higher pressure and some service-writer decided to make yours all spec. What type of lube did they use for the driveline?

[VehiGAZ]

Did they repack your wheel bearings too?

[WormGod]

MPG threads have been popping up all over the place lately. Remember, winter time also calls for altered fuel additives. This damages fuel consumption value a bit. I think we have all been feeling the effects recently.

[DK]

Did they repack your wheel bearings too?

Manual says to do so at 30,000 but they said to wait until I have my first break job -- which may be awhile since the front pads are are 8mm.

[DK]

dutchguy has a point in that it may be a more restrictive air filter than what you had before. Also, be sure to check your tire pressure as you may have been running higher pressure and some service-writer decided to make yours all spec. What type of lube did they use for the driveline?

They put in 32 psi. I don't know the kind of lube but they added LSD to the rear diff Maybe that's the problem. The VX is hallucinating.