It turned out fine, they're both full synthetic.

0W40 is just for colder climates and that's the only difference I ever heard of.

 

As of 2010 cars, all MB's come with 5W-30 in them. As for which 5W-30 or 0W-40 you should use. Fully synthetic is the key. Brand is just that, a name. For me, Mobil1 0W-40 and 5W-30 are the same price so I go with 0W-40.

If you can't find 0W-40 and you are in a cold weather climate... I would think 5W-40 would be the best, but I'm just taking an educated guess.


My preferred brands are: Royal Purple and Mobil1. My $0.02... or should I say $6.99/qt.

 

50 is too much. These motors are very close in tolerence and that may not protect as well.

 

Bought 8 quarts of Mobil 1 0W40 at Pep Boys today for my next oil change (have 1/2 quart left from the last change). About the only place around here where I can find it.

As to the comments regarding the recommended oil for the XFires, I thought I would attach a copy of the M-B recommended oil covering the various model years.

Straightened out the PDF file. Should be better to read now.

Later,

 

So, would a 2005 Limited be alright with the synthetic oil recommended for 2004 and under? I can't see how any synthetic oil from 0W40 to 5w30 to 10w30 or 10w40 would make much of a difference. Most synthetics have great cold weather start-up flow and high heat thresholds. I think we're making a big deal out of nothing, unless you constantly redline your car...