I just bought a excellent 1998 Volvo S40 1.8 16v, and everything about the car is excellent, it's been serviced all it's life at Volvo garage's with original Volvo parts.
The only thing wrong is my mechanic found some moisture in the engine oil, he said it was because the car had been standing still for some time, and only been out for very short test drives (and it doesn't useany of the coolant).
He said I should drive some long trips at low RPMs, if that didn't help it might need a new head gasket (or at least I think it was a head gasket).
How long does it take for the moisture to "go away" if my mechanic is right?
Any thought's?

 

Sounds like he is right.
Change the oil and take a few long trips.
Then try to take atleast one long trip a week.