On the subject of engine oils, I think my Aero has been on mineral oil or semi-sythetic for its life thus far (80k). Is there any point in changing it to a fully sythetic, or just sticking with a decent semi?
Better to use a fully synthetic oil (Mobil 1 Motorsport is what I use) for a 9000 Turbo. If you've modded your 9000 Turbo, it's also worth servicing your 9000 every 3k miles to ensure maximum protection. (Of course it depends what you've done in terms of mods). ;o)
i've used mobil 1 fully synthetic in lots of fast cars. i started with mobil 1 at 95,000 miles in both a BMW 535 and my current 1989 9000 turbo! oil consumption zero. if the engine is in good condition then the better the oil the better the protection it affords. if the engine is cooked it is too late to worry about the oil.
very good prices from teesside autotech who are in thornaby (sandwiched between middlesbrough and stockton) and do mail order (01642)617626. they are BMW experts, bosch injection specialists and nice guys. shame i live 300 miles away from them now!
I've been told that on high mileage cars it's better not to use synthetic oils - I tend to use a main brand oil eg Castrol, but flush the engine when changing oil & do so @ 4-5k miles, before the oil breaks down & gunks up