E53 8 cylinder Block Drain Bolt Problem/Question

[jp99]

E53/M62 2001 low miles at 40k --- have had a chronic coolant leak since new that triggered "Coolant Level Low" dash light but, until recently, never had an obvious floor drip.

Dealer could never find the problem but over time replaced expansion tank cap and then the expansion tank. Never really solved it so I just added distilled water and coolant to the expansion tank every 6 to 8 weeks. And remained unimpressed by BMW quality for this and other reasons.

Finally got noticeable drip and took it back to the dealer for diagnosis. After a false start on their part and my insistance, they put a competent tech on the case and finally pinned it to the left side engine block drain bolt. Viewable only by inspection camera, this bolt is behind an engine support and showed acitve coolant dripping and staining/crusting of coolant that had evaporated there and in that area over time.

The same bolt attaches a drain extension pipe from the block out to an accessible area where there is an access plug for left side block draining.

Repair requires dropping the differential and struts, etc - about a full day labor and about $1300. Pricy.

My inclination is to get the repair done and then ask BMW North America to assess the failed parts and explain why I shouldn't be compensated by them for a repairing a defect, given that that leak has most likely been there since I purchased the X5. Given my experience with the dealer ("they all lose a little fluid") I have little doubt that they operate on the basis of 'no obvious leaks - let's not worry about it' - few owners keep their cars long enough, anyhow.

Any thoughts appreciated, especially regarding experience in negotiating out of warranty claims like this with BMW-NA.