I have been running ethanol free premium fuel about 80% of the time and 10% ethanol the rest, but at $4 a gal. and 13 mpg Is Premium Gas really worth it? Or am i the only one not just using 89 octane.0_o

 

I use premium religiously. Here in California premium is 91 octane rating. Me mechanic describes it like eating high calorie food, he believes that you get better MPG with higher octane rating.

My 1.5 cents.

 

Absolutely. The higher compression needs the octane to prevent knock and generally running like crap. Premium up here is 93 and it makes the truck run beautifully and mileage is improved, about 18.5 highway, 14 around town, 16.5 consistently avg. Drops by 2 with crappy gas, plus runs a little rough, at least in my experience. Given the gas prices, definitely tried to go lower

 

I believe the manuals calls for it, that said higher octane can give better mileage cause it burns more completely, there gets to be a fine line between more, Power/ mileage and wasting your money

High compression engine yes high octane is needed to run properly or you can get pinging and knocking due to detonation and over time can cause damage

In our low power engine that is computer controlled I am not sure we need it, I have run premium and see no difference in performance, my brothers trans with the ram air 350 yes it does

Also remember ethonal burns faster then gas so you get crap mileage running it, don't think i ever got more then 13 MPG in my rover and that is super/ hwy

Not sure what octane is sold in UK that could be reason for the books rating

 

I run midgrade. Never seen any significant mileage difference between mid and premium. Certainly not enough to offset the price difference.

 

At approx 9.35:1 I do not consider my rover high compression, we run a small block in an s10 +.30 with 13.5:1 pop up pistons that is high compression and needs more then high test to not ping no matter how we set the Carb and timing

Mid grade is probly the best mileage for money in the 90's d1 with above ratio, net search will show earlier models with this Buick engine came with a ratio over 10:1, ranges were low like 8.75:1 ? Just my .02

 

In Europe, mid-grade gas is right around 91 octane so they run regular gas. In the USA, high octane is usually 91-93. (premium) The few tanks I have run thru my truck have shown that the higher octane does give a bit better MPG.

 

OK, When i first got my D1 [ a year ago] i ran 89 octane and it ran fine, but i do tow so i will stick with the 91 on up. There is only 3 stations that sell ethanol free gas and that is good for my 2 cyc engines mower. The 100% premium gas is $0.20 more per gal. them 10% ethanol gas. but if no one is having issues other then fuel economy then we will see. I notice my rave owners manual does say to not use blended fuels. I will check my owners manual for the 97' model year.

 

Only ethonal free fuel I have seen is off road/ marine use

 

I live on James Island so yep we can buy marine ethanol free fuel from street venders. We don't need to go to a pier for it. But i am thinking maybe there is no benefit to using it. I was just checking.