Hi all, First post here...

I'm not trying to start another big octane war, but just a question of the mechanical effects.

I just bought a 2002 Cooper S with 60,000 miles on it (woohoo!) and having tons of fun with it.

It did not come with an owner's manual, and so I did not know to fill with 91 octane. So I have put in 3 tanks of 87 octane so far (just filled yesterday agh!, now it is 3/4 full ) then I found the manual online and saw that on this first gen model that 91 octane is Required not somewhat optional as shown in later years. In any case this is an S and with the higher compression etc etc, it's even more of importance to run the high octane fuel.

So the question is simply, would driving a couple tanks of 87 octane have caused any damage already?

Should I :
a) run this tank of 87 octane till the fuel light comes on, fill with 91
b) straight to the gas station, top off with 91, and keep doing so to phase out the old gas
c) siphon the 87 into an older car I have... messy but effective I guess
d) put in an off the shelf additive this one time till the tank of 87 is run down.

I'm mostly concerned about preventing mechanical damage. Many posts in the past refer to the possibility due to improper combustion, however I have not seen talk of how quickly that could happen - for example in this situation.

Thanks!

Cosmo

 

haven't you been getting "pinging" with the 87 octane? anyways i guess there's a couple things i would do in that situation:
top it off every quarter tank
buy some octane booster (just for this tank)
i wouldn't try to siphon the gas out (waste of time IMO)
hopefully this helps

 

Heh, I guess I have been driving old beater cars for so long I can't tell pinging/knocking sounds from a normal sounding engine... Everyone says the performance will be total crap with 87, again to me it is pretty peppy already. I'd better watch the gas pedal after filling up with the good stuff

 

lol

 

throw 100 octane on top and have it mix into 91 haha.

 

In the more modern cars, the computer will retard the engine to help reduce the pinging. You won't damage the vehicle as easily as they were 20 years ago. The only short term effect you will notice is a degredation in performance. Long term like this you will get damage because the computer can only control it so much.

I would recommend buying octane boosters that would sufficiently bring you at or above 91 octane. You will need to calculate how much octane booster you will need to fill to achieve 91 octane (no, putting in one bottle of 108 octane won't cut it). Some stations may have street legal racing fuels (100 octane generally). Usually these run ~7/gal based on California prices) where the octane boosters would be ~12-16/gal. If you can find one of these stations, keep calculating and filling up with the 100 until you're at or above 91.

 

Find somebody that sells Sunoco Cam 2(104 Oct) Racing Gasoline and go buy a five gallon can full to put in your MINI. They make ask you to sign a waiver that says you're not putting it in a street vehicle.

 

Option (a) should work fine - just drive easy burning the rest of the 87.

 

As others have said. Just drive gently and you will be fine. Have fun once you get some 91 in the car.

 

My vote is octane boost and top-off with premium. Best of luck.

 

correct me if i'm wrong, but isn't C2 unleaded

 

Isn't all gas unleaded? If you are dubious about the Cam 2 just find a station with a 93Oct or Sunoco Ultra94. A fifty/fifty mix with 87 will get you very close to the reccomended 91 minimum.

 

Realistically, a top-off with premium and a light foot on the accelerator should be sufficient. Yes, you could get octane booster and/or racing fuel, but since you've already driven a couple of tanks of 87, the computer has almost certainly made adjustments to compensate. Once you've used up the 87 and start running 91 again, it'll adjust back.

 

I run Sunoco 110 in my corvette. It is leaded.

 

UGH! i ment to say "isn't C2 LEADED fuel"!

 

Learned something new. That's why this is such a great site! I've only ever run Cam2 in 2 cycle dirt bikes. I had no idea it was leaded.

 

I have also done the same thing... Been running 87 in the car since I bought 2 weeks ago... wondering the long term effects if any of this?

I assumed the computer adjusts to compensate and i probably get 2 miles less per gallon on 87 (and obviously not as peppy).

It seems as the general consensus is that running 87 in your s is going to f* up your engine over time, correct?

 

IF you are really worried, stop by a paint store and pick up some xylene or toluene, it will be 114-116, and should get you up a few points. Convince them you aren't a druggy (last time I bought it they mentioned it was used for making some kind of drug)

 

Not really worried. I'll start putting in 89 or 93 next tank.

 

The S actually has lower compression than the "justa".....but the octane is needed to prevent preignation+detonation (ping+knock) due to the higher intake temps from the sc, and of corse the effective compression from the boost....
the most common issue from apparent prolonged use (by a prior owner?!l (of low spec low octane) seem to be burnt valves, leading to an occasional misfire, rapidle worsening to a undrivible car...
By driving gently, you are keeping the boost levels down, and temps, helping to prevent carnage....

 

You haven't done any long term harm, although you haven't done the car any favors, either. Good news is that when you finally get that tank of 91 or better, you will probably feel a bit more power and will notice more miles per gallon, since the knock sensor won't be kicking back the ignition timing.

You are lucky if you have 91 octane in your area. Where I live, it's very difficult to find, so I run 93.

 

thanks guys. Blackbomber - I put 1/2 a tank of 93 and 1/2 tank of 89... yea its a pain in the ****, but i noticed the mileage change already.

The previous owner was running 93 in it... just found that out.

~mike

 

don't run cam 2 or Sunoco 110 on any vehicle that has a Cat. It will load it up and render it useless!!!!!

 

You'll be fine.

 

If this happens again, just use a bottle of this stuff. It will fix you right up. This is one of the few that will significantly raise your octane rating.

http://shop.advanceautoparts.com/web...content=value4