deposit in oil filler cap-valve cover question
 

I have a 98ml with a 137000 miles. I notice a "tan paste " in the oil filler cap. What is the cause? I use mobil O-40 synthetic oil. I drive a short distance to work everyday ( 5 miles ).

Question 2:
Is it hard to change the valve cover gaskets on a ml?

the tan paste is common, moisture usually condenses there, the valve covers have two pieces that usually leak , neither are hard to do, just can be time consuming, hoses can break if brittle etc... the upper part of the valve cover is seales with mercedes black silicone, the few i have resealed i recall the upper part of the valve cover can be difficult to remove, the silicone usually hods it on pretty good, if possible try to use original parts.

tan goo is normal. Don't think twice about it, nothing to fix. That is, unless there is a TON of it.

Driving short distances in "cold" weather is the biggest cause of the Goo.