Why would a 1998 normally aspirated C230 require premium gas? I don't consider myself cheap so I don't have a big problem spending the extra cash. I drive a Porsche 944 turbo in which I tweak the power so octane and detonation is understood. I am buying a 98 C230 for my wife. Could it be because it just mught have a higher detergant quality?

I would not run any other gas but premium in any MB. For one the engine is built and designed for it, and two the owners manuel will tell you running cheap fuel (refinement wise) will cause problems.

Living among refinerys and working in the petro-chemical industry its a known fact that the premium fuel is refinned or pureified for a better word to a higher level. And as you pointed out more of the additives content.

It would be like having some polluted water, that you ran through a filter (good one) and then said here to drink. The next one ran through that filter as above an then another and still one more filter after that. Which water do you want to drink? The first or the last one. I know this is not the best analogy, but you get the picture.

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1989 420SEL 105575 miles
Pearl Black/Grey

1990 Chevrolet E-Cab C-1500
293,000 miles

1989 Olds Toranado Trofeo'
132,000 miles

It has a 4 valve per cylinder head and a 10.4:1 compression ratio. I think that would equate to a high enough cylinder pressure to warrant premium. Otherwise, the engine may retard the timing to prevent detonation with lower octane gas.

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Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record

Thanks Ali. I was wondering if the compression was so high. I will definitely use Super.