Solid oil

[Caleb79]

Almost overnight my girlfriends oil became solid. There is a solid substance on the oil cap and it smells like gas and it's a creamy off white color. Is this crankcase shot.... I've never seen this. Does anyone have any input, it is a 1995 Volkswagon Jetta.

[denisond3]

My answer after a question first; what does the oil on the dipstick look like?
The stuff on the bottom of the filler cap could be normal condensation/oil mix. The oil filler cap and the cam cover are the coldest parts of the motor. There is always some gases blown past the piston rings, into the crankcase. If the car is mostly driven on short trips, where the oil doesnt have time to get fairly hot, that water vapor will condense in the cooler parts of the engine internals (like the space above the valves and cam and the insides of the cam cover and filler cap), mixing with the oil to look like a bad chocolate milkshake. If the car is driven longer, like more than 30 minutes, the hot oil will boil out those impurites. In a cold climate it can take longer than that for the moisture mixed with the oil in the top of the engine to be boiled out. So some of that merengue looking slime is normal.
If the oil on the bottom of the dipstick is also muddy and chocolate-y looking - then you likely have a head gasket that is going bad. But if the oil on the bottom of the dipstick is dark and clean looking, you are probably okay. With some dipsticks there will be some of the slimy looking stuff on the upper part of the dipstick, because the top of the dipstick is also cool.
That condensation is one of the main reasons for changing the oil more often in a car that only sees short trips. I like the guidance that you should change your oil each 3 months; whether you drive 1000 miles in 3 months, or 6,000 miles. Because if you drive 6,000 miles in 3 months, it means you are driving the car for hours at a time, and the oil will stay cleaner.

Also, if the oil on the dipstick looks good, you might want to replace the oil filler cap. If the gasket on it goes bad, outside air will be sucked in, and more of that moisture will appear on the bottom of the cap - because the outside air is cooling it.