Re: Older envinrude 9.5 hp with leaking lower unit
The seals on the the 9.5 are singles, but they will hold 10 to 12 PSI for fifteen minutes or so on a gearcase with no oil in it.
If you want to drain the unit and use the fill hole or the vent plug hole to pressurize the unit, you can test it.
If you take it to a outboard dealership with a service department, they can test both pressure and vacuum.
Be sure that the nylon seals on the vent and fill plugs are good.