I couldn't find specs either. So I went with a "two finger" snug. Unfortunately i used a small amount of blue loctite. No lock washer so i thought loctite would be better.
You bring up another option with anti seize but the old residue on the threads was more blueish and dry rather than grey and stainny.

I'll certainly research more but will not take any chances and i'll back them up this weekend to break the loctite.

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His : 2005 X5 4.8is (SOLD)
Hers: 2007 X5 3.0si (SOLD)
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Retired:
1999 518
2000 323i
2002 M3 (beautiful car)
2003 330Ci