filter

If you are referring to the Pollen filter the dealer is probably the best place but you might want to contact your FLAPS

what's the big downside of using generic oil filter?

Using the wrong one can be detrimental to the wear on the engine. Some filters (the orange ones) have a reputation of breaking down and clogging the oil journals which can ruin your whole day.

There has been a change in the specifications for the oil filter. The new specification is the same brand (Mahle AFAIK) but is a lot larger in diameter which probably allows a higher / unrestricted oil flow volume.

TonyJ '98.5 1.8TQ APR :)