Hey guys I've been running 91 Octane for about 4 years straight now. I run a Superchips tune. Do you think there'd be an issue going back to 87 now? Will the engine balk at it you think? My initial thought is that it'll be fine. But it's been a long time and I wanted to know what you guys think. Thanks very much.

 

What tune are you running? You should run the octane the tune calls for. If your tune calls for 91, do not run 87. If the tune calls for 87, you ae wasting money running 91.

 

Sorry, I should have explained myself better. I intend on changing back to the 87 Performance tune. I just wanted to know if there would be any detrimental effects to the engine itself by going back down to 87.

 

Nope, none.

 

If you are altitude you can run the 91 tune at 87 octane with no problem. I'm at almost 6000 ft and have been running that way since new with zero problems.
The higher you are the less octane is needed.

 

You are correct but I would like to add a side note that if you do run at higher altitudes then you should have a program for that so you aren't running rich. Even if you run less octane to compensate for the altitude your truck could run better with a modified tune.

 

^^^agreed^^^