My friend has a 1995 SL. He only uses precisely what is recommended by Mercedes when it comes to maintenance. Does anyone know if synthetic oils have been approved by Mercedes for use in the R129 SL's? If so, does anyone know which TSB approved it and where I get a copy of it? Thank you.

If he brings it to an MB dealer, they will use Mobil 1 Formula M 5w-40 if he requests a synthetic oil change. Otherwise, use M1 0w-40.

http://www.whnet.com/4x4/oil.html

I've only ran synthetic in the SL, as it offers greater protection especially in areas with a varying climate. Started out with AMSOIL and then switched to Mobil 1. Quality oil is essential to not only performance, but longevity of the motor.

my '02 SL500 has had mobil 1 synthetic from the factory, as did my SLK320 before it.

Yeah, I know. Synthetic oil is so much better. That's all I've used for over ten years now. I just wonder if Mercedes has officially endorsed them for the R129 cars, because my friend only uses what is officially endorsed... No one knows of a TSB that mentioned synthetics now being approved...?

MB starting using Synthetic Oil in 1998 with what is known as the FSS-Flexible Service System.
Please see page 3 of the attached PDF.

Fishman, if you go to www.mbusa.com , 'register' the car, you'll be able to look up the specific weights, grades, and brands of oil that MB had approved for the model year car you're interested in.

Bob

Ok, great. Thanks guys.