marksinger33772

Recently, my 2001 C240 had excessive carbon build-up, and had to be cleaned. The tech stated that I did not have to run premium gas in it, and could use regular. MBUSA says to run premium. The service manager also stated that I could use regular. I don't want to void my warranty, and am awaiting a written response from the manager. Has anyone heard of this, and is anyone running regular now?

mleskovar

91 Octane is recommended by MB. Carbon build up? I find that hard to believe with today's microprocessor controlled engines. Sounds more like they don't know what's wrong with it. Do you spend way too much time at idle? What kind of gas mileage are you getting with what kind of driving? Something smells fishy with their diagnosis.

marksinger33772

They fixed it under warranty - something having to do with the valves, and now the engine runs much stronger, even better than when it was new. An added benefit is that I am getting about 3 mpg more out of it.

jrct9454

MB is adamant about using at least 91 octane, or whatever is the highest octane available if you are at higher altitudes. They mean it. It is hard to imagine an MB-trained tech who would recommend otherwise - this is silly, to say the least.

Using lower octane for extended periods of time means the timing will be retarded, lowering both fuel mileage and performance.

vinitac

I just bought a C240 used and I am having creaky noises as I go over bumps? They guy I bought it from says it has gas shocks and will do this when it is cold? Is that the case? Also does anyone know of a good Mercedes mechanic in the Sacramento area that is not at a shop who wants some side work?