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
Sunday, March 19th, 2006 AT 2:04 PM