I'm stumped on a question of some significance to my pocketbook and the welfare of my truck. I live around the 6,000' level just outside of Denver and do most of my driving at or above that altitude.

The question is concerning what octane I should really be putting in my vehicle ('03 QCab, 4.7L). The book say's 87. The dealer say's I can get away with 85 because of the altitude I operate the vehicle at.

I'm perfectly willing to pony-up another $0.15 a gallon for 87, but I'd kinda like to know what advantages 87 will provide (if any) or technical reasons I should be doing so.

At the moment, my truck doesn't seem to be complaining.

 

Run the 85 if you stay at that altitude, if you go to sea level, run 87.

 

yeah if your that high 85 should be fine if you hear it start to ping then just run 87 or keep some octane booster in it. if your worried fill it up with 85 and really get on it getting on the highway or something if it pings then you can put 87 in it to fix it my truck sometimes pings with 92 with the superchips on performance so i run 93 but other times its fine so it all depends

 

I run 85.5 sometimes... Moslty run 87 or 88.

 

Run the cheap stuff unless you're leaving the state. Guaranteed. I ran the cheap stuff in Loveland and Meeker and never heard one ping.

 

Lowest I can run is 87

 

agreed.

 

the higher up in elevation you go the least amount of octane your engine requires.

 

They don't even sell 85 in the northeast. Or least I've never seen it. The lowest we get is 87. I'm guessing that is why ramguy said the lowest he can run is 87?