My 2001 X5 4.4i has had clattering noise on startup since 45000 miles (has 110,000 now). Dealer insisted it was normal, despite my efforts to get it diagnosed and repaired under the 100K warranty. I now use an independent shop for service, and they told me the noise is from worn HVAs that are bleeding down. Said the HVAs are something like $25 each, and there are 32 of them. Plus, the labor alone is north of $1,000. They didn't think it would hurt anything, and to only consider a repair if the top of the engine is apart for something else. Said to be sure and use the BMW recommended oil weight. Has anyone else had this problem and what did you do about it? The engine sure doesn't make pleasant noises on startup - and it doesn't do it every time.