So, the suggestion (requirement) for 89 octane fuel is not about clean but rather stable fuel.
Diesel engine combustion explodes without a spark plug to ignite it based on engine operating temperature and high compression ratio. *boom The same with a *clunk *clunk *clunk pile driver on a construction site.
Reciprocating aircraft engines are high compression ratio as are race cars. They require higher octane fuel, more stable fuel, LESS explosive fuel.
Our HEMI is a little higher compression engine than a Toyota Camry and therefore benefits from more stable fuel... BUT, the PCM computer can find a solution to 'deal with' lower octane fuel by retarding the spark plug timing advance.
... at the cost of MPG
If mid grade fuel is not available at your service station, you can hand mix HiTest and Ethyl
At a mid-grade pump, that is all they are doing. The station only has two auto fuel tanks in the ground and then mixes the two together to obtain the octane rating you desire.
Anything more than 89 octane is just wasting money.
The computer needs time to realize and re-calculate to improve your mpg efficiency. It is probably not going to happen within a tank or two, rather gradually. Accurately check your MPG by math, not the guestimate on the overhead console.
I hope this helps you.
Please return and tell how this information worked for you, what you find, and how you eventually fix your vehicle (even if it is that you brought it to a mechanic / dealership for repair)
It is your feedback and final repair report that will make these forums useful to others in the future.
Many times I search and find the same exact fault that I am having, someone suggests how to fix it, the patron follows the suggestion and then never returns to say YEA! or NAY...
The forum thread just goes dead because the person fixed their fault and has not a care to offer the answer anymore. Please don't be that guy.
Cheers!
