I guess they're not sure until the vehicle is in front of them, but the story went (with consensus) that the diagnostics of other X5 4.8ises with blue smoke symptoms always led to valve stem seals, and after replacing (several $k job) the symptom went away.

Don't ask me, I'm not a certified tech. Their explanation made sense at the time.

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2005 X5 4.8is LeMans Blue (the best blue)/Black - Staggered Chrome Style 87s. - PM me if you have alloy or black!