I use castrol edge 5w30, you really want too be checking the oil every couple of weeks depending on the mileage you do( I check mine weekly seeing as we all know the 2.0tfsi engine can use a lot). I wouldn't advise waiting till the oil light comes on, also If unsure about what oil has already been used I would just top it up for now then get an oil change ASAP,then you always know what oil is being used in your car.