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THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHPulled oil cap off today and saw yellow sludge
Leading reported evidence
Fill oil
Suggestion or failed attempt
No successful repair reported for this finding.
0
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0
Unsuccessful attempts
1
Discussions
Read evidence and context
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1
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Leading evidence: 'Fill oil' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Fill oil' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Suggestion
Don't forget to inspect the O ring on the inside of the cap to see if it's pinched or cracked.
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
14 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Generation: 20261027T201111Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Where you fill the oil. Is this common with the synthetic or whatever that put in these acrs when new. The dip stick oil is crystal clear so not worried, just curious about the residue build up. Never seen anything like that before.
Seems like I would see it on dip stick. Would I not? Also the oil level was actually a bit low and if coolant was getting in it would be high, correct. I saw someone mention yellow sludge before in the oil fill.
What you are seeing is probably just condensation. The oil that gets circulated through the engine gets hot enough to evaporate off the moisture, but you are looking at a little oil that doesn't get mixed with the rest of the oil. If it's on the dipstick, that's another matter.
I've tried the hard driving thing: Up and down the A5 and A3 from Frankfurt to (everywhere). Normal trip is 1-2 hours and driving speeds (according to Mr. Garmin) average 90mph-125mph, with occaisional bursts up to 160...(There are Mercedes SL's out there and we have a reputation to uphold)
This isn't every day of course, but I do it a couple times a week. Seems like that should be enough to get the goo out.
And that's only the residue goo. Every time I get a chance, I suck the big mayonaise blobs out with a vacuum cleaner and special adapter (rolled up cardboard).
I've only got about 3,500 miles on the car, so I hope the goo will go away when it breaks in a bit more.
Thanks for the responses guys. It is a bit unsettling to see that initially as bad things start immediately racing through your mind. I had seen the post about a guy looking at a used one to buy that had it. Many were saying blow engine in that thread, but I recall his PPI cheacking out. I tried to search for yellow sludge and etc. but could not find the right word to get the post to come up.
Don't forget to inspect the O ring on the inside of the cap to see if it's pinched or cracked. If it's damaged it can allow air into the system and pop a cell and or help contribute to the moisture issue where the yellow sludge comes from.
Yeh I get a little bit on yellow custard on the side of my filler tube. The engine does not burn oil and the cooling system is always full. I drive the car hard always. I dont think you have a problem there.
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