had a problem with similar symtom on an astra.the car was only really used for short journeys at the time. was told it was condensation from the engine not being burned off.the discharge was only on the filler cap and not on the dipstick.further investigation found the engine breather pipes were chocked with this gunge.all pipes were removed and cleaned.vehicle is now doing longer journeys and has no gunge.
xs11
January 2011
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