rolexcomex

What do you use? any harm in using 87 oct other than less mpg?

g9s8r

I haven't checked my manual or the car itself since I am new to MB but, I believe 93(or 91) is required. I may be wrong though. At least with higher performance vehicles it is so that you eliminate knocking.

MB-Dude

Get ready... This is one of those highly-charged topics! For the record, I use 93 octane exclusively. I prefer Chevron/Texaco for the Techron additive, which is approved by MB.
Cheers,
Jeff

C280 Sport

Agreed. This topic has been beat to death but still its a propor question and we should put in. I always run the highest octane. MB says do it just do it! There is a reason why. Now where I live in NY I use either Mobile or Hess. Where I live in FL I use Shell gas Mercedes have a high compression ratio. They need premium fuel. You will notice the differance in performance and MPG as well. Prime example is Mercedes 113 and 112 engines have I believe a 10:1 compression ratio, which is higher than most if not all American engines produced today. My MB owner manual says use premium fuel Seems like every time the price of gas goes up this subject hits the forum. You're driving a Mercedes-Benz. Its a premium car that needs premium care---take care of it!

Pay now or pay me the later the old saying goes.

Zax63

my e63 was 11.3 to one compression. You are a new poster, so don't know what your level of expertise, but here is my understanding of these motors and octane. Contrary to all of the advertisements on TV, Octane does not make your fuel more potent, it makes it less potent. Octane is an ignition retardant, preventing fuel from going up in flames before the spark plug wants it to. At 11.3 to one you are going to get pre-ignition on 87 octane, probably 89 as well. I don't care what you do to retard timing, you are just compressing the hell out of the fuel air mixture and you are running the risk of pre-ignition if you are driving the car mildly hard. The car will do the best it can to pull timing and protect your motor; any car in america has to be able to run on 87 octane fuel. But they don't say run well. You are going to at the very least lose power, at the most damage the motor. If you have a bi-turbo 63 - yes, you are running less compression. But now you are running boost, which is worse. So now the motor, sensing preignition, will pull boost as well as timing, reducing power output. IMHO, run at least 91. Or sell the S63, buy a s550, and run whatever you want as long as it ain't diesel.

C280 Sport

Even the S550 Needs high oct gas. You cannot run 87 on any S550. You could get away with it during a time when nothing else is available but cant make a poor habbit of it.

mrbenzes

Ive always heard that lower octane will give you ping on hard acceleration. Dont put more than one tank through at a time in a pinch...Drive your toyota if you want to buy cheap gas.
My benzes heve required premium since the 1970's, and I only put Amoco ultimate (BP 93) in them.
Mike

Zax63

Agreed. But you are less likely to damage the motor IMHO due to the lower CR.

C280 Sport

Less likely to damage the engine on lesser oct on a 550 vs the AMG model due to the S550 having less of a performace engine.