kettlinton

Hello all, I am new to the site as well as new to the Mercedes. I have now, a 1990 420 SEL with 172,000. It runs great. I do not have a owners manual yet and was wondering what weight oil it takes and what kind you guys recommend. Thank.

NZ_Benz

You have a W126 not a W140, oil weight is mainly to do with the temps where you live and how easy it has to be for the oil to flow. A decent mechanic where you live should be able to tell you.

Untertürkheim

Mobil 1 0w-40 if you get very cold weather, which is probably the case in DC. M1 15w-50 is good for warmer climates.

BENZITCH

I have some 126's and only use oil that are not synthetic.
I like the every 3k miles get to look around oill changes.
I use a 20/50 in all seasons, but my cars are garaged.
An older car is not really designed for synthetic oil, I have found friends, with 126's, to experience leaking problems after switching to synthetic oil.
Bruce
BENZITCH

Rod Spohn

My thinking is.... its not the synthetic oil that made the leaking problem. The leak was always there but the thinner flowing synthetic will only be able to flow out easier making it seem worse. The same type of thing happens when you use motor flushes on an old engine! I still change my oil between 3 & 4000 miles. I guess thats like you said to get that " look around" peace of mind. That being said - any good quality oil, syn. or not is good if changed according to driving habits, weather, dust etc. . I would question to thick an oil unless you live it a very hot area, hay thats just me though.