Passat is losing oil
This is for all VW owners new cars or old cars.Use 20w50 motor oil only for gas powered engines.Unless you live in sub zero temp. 20w50 oil will prevent oil burning if it has not started.All the independent VW repair shops know this info.VW sacrifices the piston rings in the motor.I have rebuilt many VW motors and the majority of the time the piston rings were the only problem,all other spec were in tolerance requirements.The correct weight and viscoity keep the rings from waring down.The 20w50 also keeps the hydrolic valve lifters from colapesing .If you have oil in the air filter it is because your rings have seized to the piston due to incorrect oil.