Now i'm well aware of the tendency of the big six to drink oil, but it's been using quite a bit, I'd say a good litre every 500 miles, maybe even more! It feels like I'm constantly feeding it (expensive) LL01 5w-30. Milage is on 133k now.
I've change the oil separator and all associated pipework (December) which didn't seem to help much. Lately I've changed the oil filter housing gasket (which was leaking a bit), the Vanos seals and the valve cover gasket but haven't seen any noticeable reduction in consumption.
I can see no blue smoke from the exhaust on startup. MPG seems ok (indicated 37 on long run at 70mph, 26 around London) and power seems fine.
What are the most likely culprits, and will they be mega expensive to fix?