Do you think the octane level effects milage? If so, is it worth the higher price?

 

I usually use BP or Chevron, & always 87 octane.

 

Octane rating has no effect on fuel mileage. For a stock motor, use what is recommended- 87 octane. Anything else is a waste of money.

 

At 10.5 - 11.0 miles per gallon, I but the cheapest 87 I can find and the truck likes it. I don't get and spark knock even while towing.

 

I run 91..... that's because I have the SCT 91 octane tune loaded up

 

Superchips tuner calls for 91 octane or better. The performance is much better on my 1998 XLT.

 

On a stock truck, there is absolutely no benefit to going with a higher octane fuel.

 

I agree that 87 octane is just fine for stock engines. But I don't like that high altitude 85 octane regular that they sell in the Rockies. I switch to the 88 octane plus when I am back hom,e in Utah and Idaho.

But here is a question I am curious about. Is there any disadvantage to running the high ethynol stuff they sell in Nebraska. Any harm to the motor on a 99 4.6l??

 

There is if your ECU is tuned for it...