I would concur with the advice to clean the flame trap and associated lines. I have had to do this about each 30000 miles to correct or avoid the oil leakage you describe. Not doing it will result in high oil consumption and blown oil seals sooner or later, due to excess pressure in the crankcase. If it was not done before you may have lots of sludge built up and would need to do a thorough job to ensure all the passages are really clear. In my experience with various cars, mechanics (especially dealer mechanics) who do "routine maintenance" or "xxxxx mile service" sometimes neglect to do the maintenance of the crankcase vent system.