when I was a wee child, friend's father rebuilt the smashed teak handrail on their motorcruiser with JB weld. If you looked close, you could see the lines where it was holding it all together, but that rail was still in one piece 20 years later
There are many good brands of two-part epoxy, JBWeld just happens to be one of the more time-proven brands. As I recall it is epoxy with iron dust added so it handles heat better, but whatever it is, it is well known for heat resistance (which a lot of epoxy is not) and stability.
There's another small old brand calld "PC-7" which used to come in two cans or two film cans, and mixes up more like MarineTex, as a heavy consistency paste. I've got one repair that's 50+ years old from that, still holding perfectly well.
Is there other stuff that's just as good? Probably, from the big brand names. But when you know something works...why not stick to it?
The whole trick to any good eposy repair is to clean and degrease the parts thoroughly. Roughen if needed. Follow the instructions! Especially about mixing and curing.
Would I use JBWeld instead of a real metal weld on an engine block? Well, if I had to try something to get me home, why not?
sorry! it was PC-7 not JB weld that my friend's father used to repair their motorcruiser. I had completely forgotten the name. That 33 Owens was mostly PC-7, bondo, and questionable wiring. The fact that it was still floating last time I saw was a testament to the buoyancy of wood
My son in law (an ex-army hummer maintenance guy) used JB Weld to repair the radiator on my daughter's minivan. They are now talking radiator replacement. But then I had to show him how using hammer/drift pin on a bolt under torque can pop it loose.....so idk...