that's basically what i was saying, the higher weight isn't always good in the colder weather and it's gonna be in there over winter so i'd use 10/40 fully syn over the winter months, as for the noise, this is the first subie i have had and i was coming up a hill at 40mph one day in 5th and everytime i went past a high side i could hear my engine knocking, i dropped a gear and it was fine, back up to 5th and heard it again, went into asda car park and had the boonnet up listening at different revs and it seemed fine, turned out it was a chunk of heat shield that had rusted through where the nuts were and was sitting on the manifold, it only rattled when the engine was more prone to wobble i.e. at 40mph in 5th up a hill, makes you worry though when you first hear it, but yeh mines always noisy when first fired up, goes when warm, typical subie noise i think and i wouldn't worry too much