With the price of gas these days, is it necessary to use premium gas? Can I alternate or just use a lower grade?

Not the time to think about this. Most all MB models now take high test. Modern engines designed for high efficiency push the combustion process to the max. Turbo or Supercharging makes it worse.

The problem of low octane fuel is that preignition or detonation can destroy bearings and ring lands and burn holes in pistons. Higher octane fuels actually burn slower, more predictably.

Modern systems will actually retard the timing up to fifteen degrees by cylinder as knocks are heard and transmitted by the knock sensors. This means that the car will try to make up for the improper fuel. This saps the power so drastically that fuel mileage must drop. This poorer combustion does no good for the engine and carbons it up.

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

[This message has been edited by stevebfl (edited 04-30-2000).]

For any turbo or supercharged car, I think that it is imperative that you use a premium fuel. The possibility for knock while under acceleration is very high. The higher octane fuel will help with this.

Let's see, if you are driving 20 gallons of fuel out of the car in a week, This would be 400 miles if you get 20mpg...That would save you what? about $2.00 a week in fuel if you used the lower 89 grade?? I just don't think that the risk is worth it.

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Benzmac:
Donnie Drummonds
1992 500E (very soon I hope :)
1981 280GE SWB
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

[This message has been edited by Benzmac (edited 04-30-2000).]