My" go to" sealer for most water, oil, and gasoline gaskets is Permatex "Super 300" It's a dark brown, almost black brush-on liquid that remains slightly pliable more or less forever. It's not the same stuff as the chocolate brown "3-something" Permatex (3-D or 3-H) as it was specifically designed to resist aviation gasoline in the mid-1950s or earlier. It's available on Ebay.
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!