Mighty Shilling

My car likes it's Shell 91 octane... anything else, gas mileage goes down the sh*tta

L8 APEKS

I only use 91. That would be especially so with an aftermarket chip.

Jay Gratton

Thanks for the info. I didn't know that. - Jay

M758

With a stock chip run 87 in pre-88 944s. No need to run any more. In and 88 run 91. This is due to higher compression ratio in the motor. In 951 run 91 or higher.

I have used various brands of fuel and have never noticed a difference in performance. I run the cheapest I can find which is often the Fuel from Costco with 91 or 87 as needed. I even run 91 costco gas in my 944 race car. Works great.

ljibis

I follow the recommendations in the owner's manual - 91 RON (87 CLC or AKI (R+M/2)). I don't go for the discount gas, though. Generally either Mobil or Shell, or sometimes "Blue Planet" which is what the local Holiday chain sells. It's made locally, so I figure it's generally fresher.

My stupid Audi needs 91 AKI...which hurts a little these days. I never thought I'd see $47 fill-ups for a sedan.

GlenL

Alcohol has 1/2 the engery content than pure gasoline so running the "non-oxygenated" will get power.

No sense in going to higher octane. Run the 87. Cheaper, too.

I have broken that rule by running pure 92 in my '87 NA at the track. Wanted the extra power and knock protection. There's some argument that higher octane will make less power as it burns less quickly. I'm pretty sure tht's less of a loss than the gain from not having the alcohol in there.

Picking brands is really a crap shoot. Most gas comes from the same local refineries. They have unmixed stock gasoline and then mix it with additives to make octane and the brands' detergent packages. They do this right in the tanker when it is getting loaded.

yellowline

Should say it on the back of the fuel filler door too.

FletchDM

...Unless some PO removed that sticker to save weight.

Giantviper

IF there is a chip in your car it probably requires at least 91 octaine as most of the remapping done is for the use of higher octaine fuels.

In my car i use either middle 89 or hightest 91 grade fuel. one time i did fill up with 87 and found the car not running as well as it got less gass milage and felt a little sluggish. I recommend not using lower then 89 octane iin our cars.

shmucklebuckle

No prob Jay.

OhioState944

Thanks guys. I'll definitely use 89 octane from now on. But I think I might just try 91 to see if I can notice any gains or losses. I personally am also a fan of Shell and Mobil as well, every car I've owned seems to run better with their gas.

nine-44

91 RON is actually how europe rates the fuel quality, it's the equivalant of roughly 89 in the USA. It's research octane number, I forget what the US spec is... Basicly metric, lol

Rock

with 87 I heard a knocking in the engine. With 89 that knocking went away.

I read an article somewhere that said older cars develope "hot spots" in the combustion chamber, in which running a higher grade fuel would help the engine or something.

GlenL

I run 87 from whatever gas station the car stops at. The car runs just fine.

Running a higher octane when it is not needed can create an "octane queen." The higher octane burns more slowly and cooler and actually creates carbon deposits more quickly.

For the chipped car, go with 89. For stock cars, use the spec'd gas.

nine-44

Carbon deposits are what I meant by loading the engine up. I've seen some bad ones too. We had a 928S4 come through the dealer I worked at that was so carboned up that it compressed the carbon and pushed the head gasket out on 4 cylinders. Actually it sat for 9 months and when they tried to start it it locked up. The carbon fell into the cylinders from sitting. I also noticed cleaner looking spark plugs after I went to 89.