87 vs 91

High octane only makes a difference when it is needed because of high compression, high cylinder pressures, and high heat.. But if lower octane is causing detonation, and knock retard.. Then you need to go higher. If a vehicle can run just fine with no issues at all on 87, then running 91+ is pretty much pointless. But any issues at all is the key. Slightest detonation can beat up your pistons and combustion chambers and valves in a hurry.

 

I have a 2005 with the 4.0. In my owners manual it recommends 87 octane. Most of the gas stations in the area have 87 as Regular gas except for they have 88. If I am filling cans for my 4 wheelers I use the supreme which is 90 and I will fill the truck with that and I have noticed the truck doesn't get as good of mileage.

 

I run premium in my chainsaws. On the rare occasion when trying premium in my Tacoma I got slightly worse mpg and paid an extra $.40 per gallon.

 

ive still bout half a tank of 93 left, I'm gonna mix it with 87 or 89 and see what happens.

 

These threads man....