Dear Forum members,

Sorry forget to mention valuable data:

1. Mileage shown as 163K km but taking into account that I am not first users I am sure that it could be 400K km:



Engine temperature also good (even in summer when it were +40DEGC outside)

2. Engine is SLK 320 M112.940:



3. I have changed transmission oil on 150K (16K before) and I think I was first do this on this car because old transmission oil odor was terrible. I am using "Petro-Canada ATF D3M" transmission oil now (covering MB 236.10 requirement):

https://lubricants.petro-canada.com/en-ca/brand/atf-d3m



4. Engine oil change I am doing every 10K km and last time it was on 156K (7K before). I am using "Liqui Moly Super Leichtlauf 10W-40" engine oil now:

https://www.liqui-moly.com/en/super-...0315.html#9505

5. Currently I filled my car with distilled water for tests (on 155K when I discover the issue). I thought problem was in coolant quality - before it was very oily unknown substance. Today I have picked small amount of "distilled water" from expansion tank and here how it is looks (also oil):




Also there is oil spots in coolant:


I think coolant is not ok even if keep car temperature stable.

6. I am driving car almost daily for 20-30 km for last 8 month (since I have purchased it)
7. Shop told me that this look like transmission oil. I check it in transmission shop and they tell me that transmission oil level is ok and there is no water containment in transmission oil (unfortunately has no pictures of this)

Thank you for support
Iskandar