Originally Posted by
rcterp
Trust me on this one, I sell this stuff for a living. The blue is good but rated for larger fasteners (1/4" to 3/4" with about a 180in/lb torque breaking point).
The purple is specifically designed for fasteners under 1/4", brass, aluminum, etc. The breaking point is about 53in/lbs.
Maybe its possible there are different strenghts of loctite that are also blue? The blue loctite I use, in the driveshafts for example, take almost NO extra pressure to break free... a small little "tik"... and its out. Nowhere NEAR enough resistance to strip the head.