Aviex #3 is a really poor brush-on sealer that predates Super 300 by several years. +3 is kind of chocolate brown- - - -300 is almost black, and it's a much better sealant. I've used both types for 60+ years, and there's no comparison at all. Too bad they've chosen to discontinue the good stuff!
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!