i'm going to be servicing my BHF's valley pan gaskets and oil check valves, and probably scraping gunk out of the intake runners (again). in the past i've noticed some looser intake manifold bolts, so i think i'll apply Loctite to them. if i recall, properly-applied Loctite shouldn't change the torque spec of a bolt...?

Loctite "Blue" 242 is your standard medium-strength threadlocker available at hardware stores, and is rated to 300F operating temperature. there isn't much in your engine that should normally exceed 300F, but it's possible if the engine overheats. 242 is fine for most stuff, but i wanted something with a higher temperature for a margin of safety on engine and brake components.

enter Loctite 246 "High Temperature, Medium Strength Blue Threadlocker", rated to 450F continuous. it's used the same as 242, though it has a somewhat lower breakaway strength. it's harder to track down in stores (i got some from an industrial supply place), but it's readily available online and is the same price as 242.

is your engine going to fall apart with 242? no, probably not. but i figure the 246 was worth it for the same price with 150F higher operating temperature and a modest tradeoff in performance.

side note: do not EVER use high-strength "Red" Loctite on anything unless you know exactly what you're doing! high-strength requires the use of high-temperatures to remove, usually applied with a torch. these temperatures are enough to melt or ignite hoses, fluids, and insulation in the close quarters of an engine bay.

- emilio