suntubi

With premium gasoline approaching $2.50 ++/gallon, anyone have any opinions on the topic of using mid grade gasoline to save some money? Anyone know if different models or engines behave differently than the others?

schwarzwagen

Uh, I would not recommend it. Try to drive less, you will save more there rather than running the risk of destroying your engine.

suntubi

Jon do you know something about the topic, such as some case history or MB study? Or are you just giving us safe advice?

schwarzwagen

I have no scientific research to provide, no. I would say its just play it safe advice. The car was designed to operate with premium fuel, so I would say why give the engine a reason to fail?

I have heard of people using mid grade and getting spark knock/detination under heavy load conditions. Detination will kill the engine at some point. Take for example, the '80s BMW M-Power engines, they never ran quite rite on US pump gas. The US gas never had quite enough octane for the highly tuned M motors, so after 100,000 miles or so, they self distruct its just a fact of life for '80s M owners to have to rebuild their engines after 100,000 miles. The same holds true in your case, yes you can run mid grade, but over time I would bet that your engine will wear out prematurely.

Jer

It is possible to run safely on <93 octane, but the ignition timing must be retarded. The R16 resistor for the EZL ignition control must be modified to retard ign. timing. On European models this can be changed by knobs on the firewall. In the US the resistor is a plug connection which was not meant for driver-changing. However fuel economy and power will suffer.

GDawgC220

I know that on the MB's with ECU timing retardation, you can run any grade of gasoline safely. it will lower the timing for the lower octane so that the engine will not detonate.

I'm not sure on the older models though, possibly may need dealer involvement to adjust that?

Jer

It is easy to adjust the reference resistor on the older models (EZL ignition w/ KE fuel injection, and maybe LH). The resistor is strapped onto the A/C line to the right of the air cleaner.

MBDriver

I dont think that you can actually save money on changing the grade gasoline you pump. You will, but IMO its not worth the risk and hassle. The way to truly save worthwhile money on gas is to drive less.

Jer

Yes, I do not agree with using crappier gasoline. Either be more conservative when you drive (avoid long periods of idling, fast acceleration), cut back on mileage, or both.

MBDriver

It now costs me twice as much to fill up with premium. If I use 87 or 89 grade it will save me about 1.50 for the whole tank.

suntubi

anyone ever try Octane Booster? A tankful cost difference for me can approach $8.00!

MBDriver

But octane booster costs about $4.50/per tank, so the total savings on a tank is $3.50. I dunno if its worth it to go this route.