E320 Rear Main Seal Leak stopped with Mobil 1 10w40 High Mileage Oil
 

I have a 2001 Mercedes E320 with over 280,000 miles, it had a small RMS leak and I tried adding 2 cans (600ml) of LM Motor Oil Saver to the 0w40 that was in the engine. Small RMS leak remained.

A few thousand miles later it was time to change the oil again, that time I installed 4 quarts of M1 5w40 Turbo Diesel Truck, 4.5 of M1 0w40 and 2 cans (600ml) LM Motor Oil Saver ... still the small RMS leak remained.

However, on this last change I switched to M1 10w40 High Mileage *and* added 2 cans (600ml) of LM Motor Oil Saver, and ... totally dry driveway, no more RMS leak.

I think M1 10w40 High Mileage by itself may have been the solution to my RMS problem. The LM Motor Oil Saver was in for almost 15,000 miles on the previous two fills and alone it didn't do the trick.

2 days after M1 High Mileage 10w40 goes in and dry driveway.

Before:
http://i59.tinypic.com/20gid10.jpg

After:
http://i57.tinypic.com/1dcom.jpg

How's it going to mark its spot:D?

Thanks for sharing.

I wonder how much the higher cold vis # helped?

Here's the viscosity comparison:
V@40c / 100c / HTHS
10w40 = 95.9 / 14.71 / 3.9
0w40 = 75 / 13.5 / 3.8

Kool 28% more viscosity. Wonder if that contributes? Do you have a link to a chart for a full range of viscosities? I'd like to look at some.

I would be cautious about assuming the leak is cured. The RMS for the M112/113 is an unusual design. Rather than a rather flexible viton lip with a garter spring, the M112/113 seal is a stiff material with no garter spring. It isn't uncommon for them to leak prematurely. I have replaced three in my cars, one at 60K, one at 100K and one at 160K. Another oddity is that the WIS states that the seal housing must be removed to replace the seal rather than praying it out while still bolted to the block. And the seal must be pressed in until it is 1mm below the edge of the housing, not flush as one would normally expect. I bought the M-B tool to do so (it actually works on the M104 also).