Hi all,
I have a question about the wrong fuel used and what to do now. A good friend borrowed my 2004 H2 and put 85 octane in it (full tank) instead of 87 octane fuel. I forgot to give the instructions to only use 87 octane fuel. It was driven up over the continental divide in mountains and back down to Denver. There was a quarter tank left in it when it got down to Denver. I put a quarter tank of 87 in and just over a quarter tank of 91 octane. Do I need to use a fuel injector now? I have not heard any engine knocking so hoping everything is ok. Any input is appreciated, thank you!

 

It will be just fine, I use premium fuel when I tow but 87 all the other time.in fact 87 is as low as we can get here.

 

Yep - nothing to fret about. Just try to keep it running 87. Even with the 85 in it, if it were to start to knock at all, the computer will detect that with the knock sensors and cut timing to eliminate it.

 

At higher altitudes, the thinner air compensates for the gasoline's lower octane, so the engine can run without detonation. If you will be traveling out of the high-altitude area, use the recommended octane at lower altitudes.

 

Thank you so much for all the responses! They were very helpful!