Sorry if this is a 'lame' question, but I don't know much about the inner-workings of vehicles.

When I use the cheap gas (lowest grade, 87 octane I think) in my 4.0L (2004), I get some pinging from time to time. Using midgrade gets rid of the problem. Is it OK to mix low- with mid-grade on a regular basis? Or should I only use one octane all the time?

Thanks!

Charlie

 

"Some" "from time to time" may not be a problem.

There is nothing wrong with mixing octanes.

If you think it is knocking more than it should I would bring it to the dealer and see if they want to look at it. Sometimes there are calibration updates for the PCM to fix problems like these.

The engine was designed to run on 87 octane.

 

will it better the life to use middle grade?

 

No. Normally it is just a waste of money. In fact I've been told by several mechanics that the higher grade fuels can actually harm an engine not designed to run on it. I'd get your knock checked out and stick to 87 octane, that's one of the reasons I bought a normally aspirated pickup truck..

 

OK. I'll keep using using 87 and if the ping comes back, I'll take it in.

Thanks!

 

too high octane for your engine can cause carbon build up and kill your fuel injectors.