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Discussion Starter #1 (Edited)
Changed the oil on our 2005 330i yesterday. Car has 63K miles on it and oil was changed at 1K, 15K, 30K, 45K, 50K, 56K, and now 63K. The car has never consumed any oil but is often driven only short distances. The oil that came out of the engine looked normal as did the oil filter and the insides of the oil filter housing. However, when I was pouring in the new oil I noticed that the inside of the oil filler cap had a slight gummy redish brown coating on it as did the inside of the valve cover around the cap. But, when I looked down the inside of the valve cover everything looked normal - shiney aluminum with a coating of oil. Since there is a shield under the cap to prevent the valve train from throwing oil at the cap, it almost seems like air/oil vapors mixed with dirt were forming around the cap and any place where oil would not wash it away. There's not much of this redish brown gummy stuff but I wasn't expecting to see any. Anyone know what's going on here?
 

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Do a search for- oil, filler, cap, deposits

There are several good threads with this issue mentioned.

"How bad is my sludge" March 2009
"Orange under oil cap" July 2005
 

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Doesn't sound like anything abnormal at all. I have that residue and most that I've seen have it. If it's foamy or light colored, then it's an issue.

Sythetic, I know, forms a film after so many miles...which film, as I understand it, is beneficial...as in forming a protective layer. Those who change oil too soon, might not get this film (think I read it doesn't begin forming until 5K miles or so), but in my book, it's good.

Doug
 

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Discussion Starter #4
Thanks for the pointer to the other threads. I'm guessing that these deposits formed because (a) I didn't do off cycle oil changes during the first 50K miles and (b) the short distances that this car normally sees doesn't create the heat to help break down/prevent what is forming. Since it's just a light coating I'm not going to do anything about it except to monitor at oil changes. I'll wait until the valve cover gasket goes to clean it up.
 

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Doesn't sound like anything abnormal at all. I have that residue and most that I've seen have it. If it's foamy or light colored, then it's an issue.

Sythetic, I know, forms a film after so many miles...which film, as I understand it, is beneficial...as in forming a protective layer. Those who change oil too soon, might not get this film (think I read it doesn't begin forming until 5K miles or so), but in my book, it's good.

Doug
Yup. It is just the oil not going completely down into the engine when poured in and it's just getting burnt. Mine is like redish brown color on the cap. After so many miles it does this. Why didn't they make it a straight shot drain down when you pour it in...:hmm:
 

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............Don't take my word for it, but on the Volvo and Mercedes, they have a similiar set up as ours with the position of the oil filter. I think on the Mercedes, they actually re-fill the motor oil through the filter instead of the cap on the valve over during an oil change, or at least you could. In one regard, it makes sense and is a lot cleaner, but don't know if there is an adverse effect on our engines. Maybe someone can elaborate on that if there is. It gives you the straight shot you are looking for though..........
 
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