Drive shaft bolt.

[jpiazzam3]

Just did the CSB I was wondering if the bolt that hold the 2 sections of the driveshaft together requires thread locker

[HennyM3]

I went ahead and ordered a new OE bolt for when I do mine, and they come pre-applied with some blue thread locker. Part number: 26117551339
So I would say it would be preferred to apply some sort of Loctite.

[ChapterM3]

I would say, yes, it absolutely needs thread locker - when I bought my car a previous owner had a shop do the CSB. After about 100 miles of driving it home loving life and my new M3, I heard and felt a big boom in the middle of my car. Long story shot that bolt backed out while I was driving at about 40mph - needless to say it was a terrible sound and destroyed the driveshaft. So yes, I'd use thread lock on there