White goop on Oil Cap? What’s the Scoop on the Goop?


So – what’s the scoop on the goop?

White Goop On Oil Cap

The goop I’m writing about is that built-up white slime you’ve probably seen (when adding oil) on the backside and lower cavern of the oil fill cap of your engine.

This formation is simply caused by condensation which has no immediate harm to the viscosity of the oil. This goop has been known to freeze (in freezing temperatures of course) and block the ventilation pipes of the crankcase breathing structure – especially seen on European engines that have tight and high volume crankcase ventilation systems due to their higher compression engines..

This blockage creates built-up pressure within the crankcase which spews substantial amounts of oil from the non-pressure type gaskets – (e.g. cylinder head cover gaskets, dipstick tube seal, etc.) and gets all over the engine and underside of the vehicle making it UN-drivable!
This issue has been addressed by manufacturers implementing insulated and / or electrically heated ventilation pipes and valves.

An old habit of longtime owners of these cars is to remove the oil cap at end of day (leave the hood open to remind) which lets the crankcase acclimate to the ambient temperature thus lessening or even eliminating the buildup.
Your car repair specialist can tell in an instant if your engine breathing pipes & valves has had the “cold weather” upgrade.  White goop on Oil cap needs attention!
Happy motoring!

Steve & Dave Hollis

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