Fuel Grades

[Will]

Ok, who uses regular gas, and who uses premium? If you use premium have you noticed an FE difference in the two?

[tasdrouille]

It depends. I buy regular for the Elantra and Shell V-Power (premium) diesel for the TDI.

[Brian03cav]

i choose regular for my cavalier, but when i had my focus i had the ecu flashed and could only use premium.

im going to on the next two tanks however give premium a shot and see if there is any difference, but i look at it as regular is cheaper, so it would have to be a great difference in FE to make the complete switch.

[ALS]

I use 89 in my DD an 87 Turbo Volvo. The owners manual says 91 but since I hardly ever go into boost why should I spend the money on octane I'm not using. 87 makes the car run poorly and it has pretty poor pick up if you have to put the pedal down.

[saunders1313]

I've used both premium and regular in my bike and have noticed no difference. The manual says use premium, but I have a small engine that just doesn't have the compression to completely burn premium.

[cfg83]

Will -

I ran Chevron 91 last year because of my HAI (hot-air-intake => lean-burn => higher octane is better to avoid knocking/pinging). I switched to 87 when the gas prices got too high, didn't notice a change, and never switched back.

I have a hankering to up the octane again because my car is *different* from last year. I also think it has been on 87 for so long that I might be able to detect a difference in the way it drives (big *shrug*).

CarloSW2

[ptsmith24]

Even if it did yield better FE, from a cost perspective it would have to make up for that 20 cents or so per gallon to truly make it economical. I wouldn't mind seeing some data on it. I'm not quite sure it's worth the gamble of higher fuel prices for few tanks, personally. I'm sure it's been looked at before somewhere.

[PaleMelanesian]

Bailout at CleanMPG, with his commute up and over a rocky mountain pass in a Yaris, tested this.
regular was best
-4% mpg with midgrade
-9% mpg with premium

I think I'll stick with the cheap stuff.

[RH77]

When I had my HAI (160F) I used premium to prevent detonation, but the cost-benefit was off. Now, intake temps are 100-120F with full advanced timing and no ping with near-full load (some knocking at high RPM, so I don't go there much).

The TSX "requires premium", but runs just fine on regular. The savings add up. FE is the same too. There's a bit of stumble from time-to-time at 6k RPM with VTEC, but again, very rarely used.

Long live 87!

RH77

[groar]

In my 11 years old turbo diesel I used only regular and mid-grade during years.

One of the rules to eco-drive is to shift up soon, but it had difficulties to stay at 1500rpm. During the first premium tank I felt changes and now (at 4th tank) it can accelerate from 1200-1300rpm.

Because it permits me to improve my eco-driving style premium permits me to have a better mileage. Currently I'm staying with the premium as while I'm saving 33% of diesel, I'm saving 30% of money. May be one day it will be the placebo effect... My mechanic maintains my car, but premium seams doing things my mechanic doesn't...

Denis.