Our 850 turbo has an oil leak I can't find. At first it was the turbo's oil return line. I replaced that seal and I thought that was the end of it. Its not! The oil seems to be leaking from somewhere on the driver's side, on the firewall side of the engine. It goes through about a litre of oil per tank of gas (that rate varied on a recent cross-country trip with the leaking more severe at high RPMs while pulling a trailer.)

One thing for sure, I've got great anti-rust protection on the underside.