Wow. I am impressed. I have never seen so many people actually notice that premium, when not needed, does not help. I know soooo many people that think premium must give better milage and/or it cleans the engine.
The only time you need premium is if you are fighting knock.

I started pumping 89 and I swear I've noticed a smoother pick up and I've imagined a bit more power. I'll have to check the mileage...

i used Shell premium fuels for 6 months straight...my gas mileage dropped about an avg of 4-5 mpg and did not see any spectacular increase in power...or at all...I currently use Regular from BP/Amoco only and have been getting the best mileage overall than from ANY other station in my area.

93 Octane from Shell = 17-18 MPG
87 Octane from Shell = 21-22 MPG

87 Octane from BP = 22-23 MPG

89 Octane from Citgo = 21-22 MPG
87 Octane from Citgo = 21-22 MPG

Just to give you an idea.

i used shitgo 110 octane in the bonny i used 10 gals at 4.75 a gal and got 13-15 mpg
i use 87-89 every other time i fillup i average 23-25 mpg with hess or cito gas nice gas mileage my neighber get 16-19 with a mini van they suk they r pi$$ cuz i got better mileage then they do


my bonny is a 93
there van is a 01 they still suk lol

The ONLY thing running premium gas in your Bonneville hurts is your wallet. Drive on.

Higher the octane, the more energy it takes to get it to fire off. That'* why higher octane doesn't detonate or knock like the lower octane.

In turn, less performance/gas mileage in an engines designed for the lower.


Patrick

Higher compression = higher octane.

Power adders (SC or Turbo) = higher octane.

If you have neither, stick to regular grade and mid if you have money to burn.