My cousin recently bought a 83 Nautique in "rough" condition. A buddy of mine who is a boat mech came over to give it a look and one of the first things he noticed was the tranny was filled with brake fluid. He said that when people have a problem with a slipping borg warner tranny they can prolong the issue (not fix) by adding this. Sure enough, once the case was cracked open, it needed a rebuild.