I have a 62 1200 beetle. I recently noticed that under the oil filler cap there was an amount of oil foam (creamy sludge). What could cause this ?
The oil was 2000 miles old. I use Valvoline xld 20w-50. I have just changed the oil and will be checking to see if it happens again.

I experienced the same with a '67 1500 and was told it was due to the detergents used in modern multigrade engine oils.

I've always used straight 30 grade oil since then with no problems.

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Thanks for that. I'll try that next oil change.

its due to water getting into the oil and it makes it into mayonaise basically, clean as much sludge out and do an engine flush and then replace with fresh oil.

This will usually happen if the car has been left to stand or only does very short journeys where engine never gets to operating temperature.

Personally wouldnt bother with straight 30 go for a 15 40 mix and change at regular intervals of 3000 miles or three months

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