I have the Syntron (edit:correction, it is the Norscott) shaft seal. Age unknown. It uses ATF. When I bought the boat 2 years ago the ATF reservoir was low. I have been going through about a pint every 50 to 60 hours underway. I don’t lose any ATF when the boat is just sitting. It does not leak any water into the boat.
I have heard that one of the advantages of a lip type seal is it won’t fail “all at once” and sink the boat, but I must admit to being a little nervous about how much fluid it uses.
Things are real tight in the area where the seal attaches, what have you folks used as a replacement? I’m pretty happy with the Norscott, just wish it were a bit less thirsty. My reading on the forum indicates I might need a whole new shaft to switch seal types due to scoring from the Norscott.
Thanks,