Don't know if it helps your decision, but I have a topsider that worked ok on my old Golf diesel, but in my c class, it takes an hour to pump the 6.5 quarts out. There seems to be something about the shape of the dipstick tube or where it meets the pan that keeps catching the end of the tube, and I have to pull it out enough to create air bubbles, suck out what I can, then pump and repeat the process. Same problem for 3 oil changes now. I'm probably just going to get under the car with the wrench from now on.

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former: 83 300D, 97 C230, 93 400E

current: 08 C300 Luxury , 92 500SL

I took a closer look and find no pressure releave button. Mine might have stuck in the auto-shutoff mode but there is no place to reset it. I might have to take the top off to see what is inside and dis-connect the mecahnism.