I don't use thread lockers all that much but when I do, on a bike, I use Vibra-Tite VC-3. Why? Well, unlike most other thread lockers (e.g. Loctite, Permatex, etc) it does not harden. It's remains malleable. Why is that important? Because fasteners don't get "locked" on the part to the point that they are difficult to remove like other thread lockers that actually harden. A hardening type thread locker can also cause stripped fastener heads trying to remove them...been there more than a few times. What this means is you can remove the fastener and re-install and you'll still have a fastener that won't back out from vibration. It's good stuff.
I have virtually stopped using hardening thread lockers on all fasteners for other non-bike applications and use Vibra-Tite VC-3 instead. If I have a high temperature application then I go with a "Blue" (medium strength) thread locker.
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