Mayonnaise
 

Hey All,

This morning I was cleaning up the X and decided to check the oil level. After pulling the dipstick, it looked to be a little low, needing 1/2 quart. When I removed the engine oil filler cap, I noticed a small build up of yellowish paste, almost mayonnaise in consistency.

I recall from earlier posts that this can be an indication of water/coolant mixing with the oil, resulting from a gasket or valve leak. The X's is running smoothly, no blatant tell-tale signs of problems. I'm just wondering if I should take it by the dealer for diagnosis or repair.

When the oil was changed in October, I used Mobil 1 0w-40, instead of Castrol 5w-30, could this issue with the mayonnaise-like build up be a result from that? By the way, the X is CPO'ed til the end of this month. Thanks for your thoughts.

The paste is a result of moisture mixing with the oil. If the vehicle is running fine (indicating no leaks in the head gasket, etc) then it is likely due to condensation. This results from short trips that don't get the vehicle hot enough to boil off the condensation. Over time, it builds up and is visible under the oil filler cap.

I would do an oil change, and try to drive it such that it gets hot more often. The conditions that lead to this build-up are the same as those that lead to problems with the oil separator/crankcase ventilation valve, since the moisture freezes.

I don't think your choice of oil caused it as much as your driving conditions.

I'll change the oil tomorrow night. I went back to check the oil level and noticed similar yellow paste on the bottom of the dipstick. Would condensation be as prevalent to this area as the oil fill cap? Thanks.

You could have your oil diagnosed by a testing company

Yes, it could still be condensation. If you had a coolant leak, and the coolant was mixing with the oil, it would be more likely that the oil level was high instead of low. You could check the coolant level to ensure that it is in the right range.

Definitely get this checked out properly. Last time I saw this "mayonnaise" was when the cylinder head cracked on my '88 325is.

After normal driving today, I let the X cool down before checking the coolant level, the level indicator is all the way at the bottom of the gauge. I've never seen it this low before. The coolant was flushed and refilled only two weeks ago. I'm starting to wonder if there was a leak that I just haven't noticed. Thanks.

Did you or do you see any white smoke from your tail pipes? Did you notice any over heating? You may have blown your head gasket. That would explain the mayonnaise in the oil and the low coolant level.

I've only noticed one irregular amount of white smoke, it occurred yesterday morning when the X was started. No over heating thus far, but I'm taking it to the dealer tomorrow morning for service to be safe.

valley pan gasket could be the culprit.