gaskets vs sealants?

thought id just add my thought to Randall's
i believe Hylomar to be the best jointing compound ever. i still have screws 
coated in hylomar from 20 years ago open in my garage and they still are tacky 
and soft as they should be.
my biggest problem with silicone is its demanding requirement of absolute 
cleanliness. with the slightest gossamer of oil it will refuse to form a seal. 
not so with Hylomar.
Merry Christmas all
Frank Fisher
58 TR3
Temecula 
California