My dealer has switched to the new Mobil 1 5W-40 ESP but I have most of a case of 0W-40 left. A have to add a quart every 2,500 miles or so (normal for S65s). That would make the mixture almost half and half by the next service. Should I worry? I understand the 5W-40 ESP is not even available retail, meaning I can't imagine what else one is supposed to do.

 

This is the only Mobil 1 5W-40 that I found on their web site. It is wrong for the vehicle. What oil are they using?

 

From what I've read compatibility is not a problem when you mix different weights of same manufacturer oils, as long as you don't mix dino and synthetic. Don't worry, be happy

 

MB is changing to this low-ash oil in preparation for Bluetec diesels;

http://www.mobil.com/USA-English/Lub...la_M_5W-40.asp

It's apparently only being shipped to dealers, who are replacing the 0W-40, per the new MB 229.51 spec.

 

The Mobil 1 ESP Formula M 5W-40 oil is appropriate for vehicles that require MB 229.51 oil, but not for vehicles that require MB 229.5 oil.

 

Dealers got a letter superceding 229.5 with 229.51 for all gasoline and diesel cars 1998 MY and later. The fact is that my dealer has switched and most are in the process of doing so.

See also:

https://mbworld.org/forums/e-class-w210/192861-has-mb-changed-recommendation-mb1-0w-40-5w-40-w210-2001-a.html

 

Yes you can mix them with no issue. Jim

 

The way I understand it is that the 0W40 stuff is mainly for mileage purpose only to satisfy CAFE standards. For someone driving a turbo V-12 mileage is no concern. If you do not live in the snow belt there is no difference between using 0W40 and 5W40.

The low ash oils are only relevent for diesel engines for the time being. That is why we should all buy high powered cars that do not require too much pampering. I dread what the future diesel engines are going to be like when it comes to maintenance.

With Rep Henry Waxwoman and Al Sore hugging trees so hard they are going to squeeze the life out of cars and car owners if not kicked out.

 

My understanding is the low-ash oil prevents contamination of the urea-injection catalyst system on the upcoming 50-state diesels. But the dealers are switching to that oil for all cars, since they only stock one kind of oil. I'm not worried about the impact on mileage -- only on the safety of mixing the 5W40 ESP that the dealer uses with the 0W40 non-ESP I can buy retail. The US hotline (800-FOR-MERC) confirms it's ok to mix the oils. They even put a record of the conversation in my file in my dealer's computer to document the factory advice. They do some stuff right!

BTW, the oil consumption seems to have dropped with 10,000 miles on the engine, as predicted by the dealer. I just drove about 1,000 miles on I-5 (mostly above 100 MPH; occasionally 130-140) and it used about .4 quart per the test-mode readout. Since it seems to burn much more oil at these high speeds than at our normal California 85 MPH, it's doing a lot better than the quart per 2,000 miles I had been seeing. Maybe I won't need to mix as much as I thought.

 

Our E500 had 65,000 miles and we had 8000 miles on the last service oil change when we left for Canada. We drove 3500 miles at highway speeds up to 75 mph sustained for hours. Upon return we still don't show the add oil on the indicator. Sorry no dip stick.

Jim

 

You need to order one of those MB oil measuring "tools"!

 

I have the website for one of those tools,, now to know where to "stick it" is important. I found the red plug on the tranny behind the pass. side rear valve cover, now where do I stick the dip stick?
Jim