Devcon Epoxy Aluminum- - - -but you'll have to heat the sensor with a torch if you ever decide to change it. Any of the "liquid solder" products would work, but if the sensor has a pipe thread like most of them I've seen, putting any sealer at all on it is a big waste of time. That's particularly true if the sensor is brass and it's going into a cast iron cylinder head or intake.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!