White gunk on oil filler cap.


Registered User
Feb 25, 2007
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:jester: I checked my oil today and found it was low. I then took the filler cap off and found the dreaded whitish yellowish gunk on the under side. Now I know that it could mean head gasket.

Any ideas.
It only means head gasket if most of your oil has white, or if the oil is sludgy and thick.

It could just be moisture vapour mixing with the oil on the cap, so its not neccesarily serious.

If the main builk is white it could be coolant mixing with the oil, have you been losing coolant?

Do you use mineral or synthetic oil?
No my coolant doesn't seems to have oil in and looks like a healthly amount too.
OK, check your oil filler cap is nice and tight, do an oil change, checking the condition of your old oil.

If its runny but dark then its fine, if its chocolate coloured then bad things are happening.

If it is fine, replace your oil with a fully synthetic, something like Fuchs Titan, Mobil 1 or similar, 0-40 or 0-30.

If it continues to turn white, I'd start worring about head gasket but that seems unlikely if you arent getting through coolant.

Oh, and buy your oil and filter from www.opieoils.co.uk, very cheap and very good.
Been using the car for lots of short runs? If you are, it won't get to full operating temp and the condensation that forms naturally in the crankcase won't evaporate properly. Try taking it for a long run and then do an inspection.
I would go by checking the oil on the dipstick, not just the filler cap. If you just have oil on your filler cap and not on the dipstick i wouldnt worry too much, may just be a blocked breather or something small.