Re: 1985 90hp water in lower unit oil
As Mas mentioned the first place to check are the two drain plug seals. If they are fine, then any of these could be the problem: two (back-to-back) seals at the propshaft, an oring around the carrier, an o ring around the shift rod, o rings around the 4 carrier bolts and a single seal on the driveshaft. Any of them can leak, and if one is leaking, best to do them all.