YMMV of course, but with these cars it ALWAYS pays to take them to someone who knows how they work. Im sure your mechanic is a "good guy" but since when has ANY mechanic in SL admitted that something is beyond his scope? They will ALWAYS say "Mahaththaya, karala balamu" and in the case of VW's and most other euro cars that is often a recipe for disaster.
In the long term, it makes MUCH more sense to go to someone who specializes in them.... Unless of course you want the thing to turn into money pit that will quickly drive you loony!