TomK [MA][99 BW 5.9L FT4WD]
tek@acm.org
I would definitely do the full-boat cleanup-and-dye route before signing up for major work.. there are a LOT of places for oil to hide after an oil change on these things.. an accidental spill at the oil fill can take a few weeks to show up in your driveway..
IMHO, unless you have a very special relationship with a/your dealer, I don't think there is much of a shot at warranty here..
I don't have my FSM handy, and I haven't personally done any bottom-end work on a 318/360, so I don't have a good idea what a rear seal replacement should cost..