From working on old outboards for 35 years before taking anything apart use "Kroil" on all nuts n bolts and let soak for at least 2 hours if not longer.....
hahaha, well... I wish I had made it up.. I mean *ahem, yeah I'm pretty clever, huh?! Pretty sure I heard it from Scott Manley on RU-vid. He's got some pretty catchy phrases.
