I went through this same ordeal... synth vs. cheapo...
Long story short, AMSOIL. every 7500 or when I get bored - whichever comes first.
The whole point of using an oil that you only change "every 35000 miles" is that when someone else buys 3 or 4 qts of oil, you bought one. Sounds like the extra cost is justified to me...
In this world of the 3k mile oil change, only one entity emerges on top - Jiffy Lube. Think business would be as good if the song was "Every 35,000 miles, just bring it in to Jiffy Lube..."? Don't think so.
Think about it...