I have another friend who wanted to buy a used X5, so I warned him about the 15k service intervals on these machines. I explained how low miles = short trips + long intervals = sludge. So I was alarmed when my GC-guzzling neighbour traded his pampered R32 for the X5. I told him, "pop the hood". It was thick reddish sludge on the filler cap, as far as I could press my finger into the valve cover and especially on the dipstick, for 6 inches up. He told me "it had oil service at 10k"...the whole "I checked into it and found ONLY what I was looking for" mentality. So, the kicker is the vehicle is a '03, only 38k...he spent $30k on it and it's sludged. We here have seen the examples of 15k intervals on BMW "Castrol" (like it says on the filler cap): http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=1;t=008933 Anyway, he's ordering ARX (8q sump= 2 bottles) and I'm stocking up on Delvac 1300S...maybe 3 changes this summer will get the engine normalized. I'll report as best as I can, but won't be removing any valve covers. I will take pics of the filters, they are canister type. Another note, the dealer (where this guys spend a MINT) told him the oil was "done", although I found it black and low. Kinda sad.