I like Permatex Super 300. It's a dark brown, almost black brush-on liquid that was developed to seal gaskets exposed to 115/145 octane aviation gasoline. It's much more effective than the standard brush-on stuff, Permatex 3D. It's a little hard to find, but I've been very pleased with it, particularly when I'm installing steel-shim cylinder head gaskets on high-compression race engines. The .023" steel gasket seals compression very well, but it has problems with coolant seeps sometimes. The Permatex dries it right up!
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!