...or will that blue stuff that is on the rotor bolts do the job?
(and is it reuseable once unthreaded, rethreaded etc.?)
The blue stuff IS threadlock
Dont think its re-ussable, I've never bothered with owt bar grease, someone will no doubt tell us shortly that high spec coppaslip is the only thing to use!
I've always just used grease too - my disc rotors have never fallen off.
I've always used just a small dab of grease too.
Wee drop of grease here too. Never had a problem.
blue stuff is still on mine, i just whack them in, never had a problem.
I just use grease, and the other day ran the 6 bolts with only 3 bolts in each! Naughty boy....
DrP
Most threadlockers are sort of reusable: they harden in an anaerobic environment (like inside threads), so in theory they are about as reusable as dried superglue or cement, ie not at all. However since most threadlockers are also fairly soft and gunky even when hardened, they will help holding the screws in even after removal by increasing the friction between the threads, much like any gunk or dirt will. Though of course they will never be as strong as they were before removal.
Even though I have the stuff at home I rarely use them on my bikes since the name brand stuff (Loctite) are more expensive than prized bull semen. I'm more concerned about the bolts seizing up, so I usually use a little grease or copper paste.
High spec coppaslip is the only thing to use or you'll die.
I actually do use coppaslip, but I've screwed them in with nothing before and not had a problem.
Whatever you use, just be careful not to use too much of it if it's a blind hole. I've seen people split mountings that way before. Obviously not an issue if it's a through hole.