White substance in the oil dipstick

EMANUELMAR

MEMBER
JAGUAR XJ6

1997 Jaguar XJ6, mileage: 84,000. My last oil change was done 2 months ago and everything was fine. Today as I was preparing to drive about 600 miles, I noticed that I had this white creamy substance (like mayo) in my oil engine dipstick. As I live in a small Town, and the nearest Jag dealer is 2 hours away (in Kansas City), I decided to do an oil and filter change immediately. The guys at SEARS told me that this problem could be due to a blown gasket, head gasket, or merely some humidity accummulated there. Does anybody has any hints? What about a repair estimate? Many thanks.

1 Reply

BESTGRIPAJAG

MEMBER
13 POSTS

All cars have some condensation, it's part of the reason you change the oil. Condensation on an oil cap in cold weather with short trips is nothing new.

It's an oil/water emulsion. Your oil collects various combustion by-products. The "mayo" indicates that your motor isn't getting hot enough to drive this moisture out of your oil. Keep in mind it takes an engine about 12 to 15 miles to throughly reach optimum temperature regardless of what the temp guage shows.

Water is one of the by-products of combustion. Which doesn't include the amount of moisture that is in the amount of air required by an internal combustion engine. (You are using about 14.5 times more air than fuel.) Some will get past the rings. As the hot gasses in the crankcase and cylinders, (and if the engine stops with an exhaust valve partly open) contract as they cool, they suck in ambient air (with humidity) which will condense on the metal parts, when cold.

All oil is designed to deal with a certain level of water content.

The oil cap may stay cool enough in cold weather to condense oil/water vapors together (yielding the white emulsion you see) take care! :D