That Lucas stuff worked miracles in my VW Golf!!!!! I had this ticking problem in my car and thought it was a hole in the manifold... Yeah... it's, but it was that loud! (3:15 am. here so please forgive me!) After running that stuff in my car... over time it's disappeared! I had problems with the car running HOT and that problem went away too! The reason I was told the car was running hotter than normal (After replacing the radiator and making sure the electric fan worked... checked all of that!) was because when you start your car, move it, then shut it off... it's EXTREMELY hard on the cams because they don't have much oil there to lubricate them... I also let the car sit for days before moving it, then start, move and shut off. That kind of stuff will kill your engine, trust me! The Lucas stuff has given me a winter beater that will last me a couple more years, rather than run scared of over heating and replacement of the vehicle.
The only thing I would be aware of is that I've heard (not sure why it freaks me out when I say this) that BMWs have tighter tolerances and it might not be the right product to use in this kind of car? I was using it at at 25% ratio in my VW (1 quart in exchange for the Lucas product) and I've had great results. I'm not sure how many quarts of oil your car uses (my 540i takes 8 quarts) but I would start with the lowest amount... one quart, then see what happens.
I'm in the same boat as you are when it comes to miracles in a bottle, but I'm truly sold on this product as it's changed the way my VW has run... I'm a believer!
Well... that's my two cents worth on that subject, now where's that pillowwwwwwww...........
-Eric