The car is a Golf Mk4, 1.9TDi, 2002.
I was checking the car after a short run and the coolant tank had bubbles on the surface; not foam or emulsion but bubbles. The car does about 800 miles a month, 194 000miles on the clock, and doesn't seem to lose fluid. Oil is ok, not sign of water in it either.
Any suggestions about this? Its not something I've come across before.
Regards,
Colin.
