do to the base programing of trucks, the lower octane fuel is best suited for use.




note:

they produce low octane, and high octane, them mix them 50/50 to make mid-grade gas.

 

Here in South Dakota, the 89 octane is the cheapest, because it's the only one with 10% ethanol. I guess they give the ethanol gases here a tax break, making 89 octane always cheaper or the same as 87.

I run the 89 most of the time, but once in a while I put in 87. I've heard both sides of the arguement on ethanol... some say the 10% mixture cleans out the engine better than normal gasoline, some say it clogs it up. I'm guessing it doesn't really matter a whole lot, as I haven't experienced any benefits or problems with 10% ethanol blend.