"Dave the term hypoid actually
"Dave the term hypoid actually referred to the way a gear was cut/shaped.
Hypoid rated gear oil will withstand greater contact pressure of the gear teeth (which actually float against each other separated by a thin layer of oil) than non-hypoid.
The term has kinda fallen to the wayside over the years and isn't commonly used anymore. Gear oils now have a "GL" rating.
Most "Marine" gear oil is EP (extreme pressure) GL-5 rated (which makes it both (hypoid) and water (resistant) - suitable for the marine environment.
So you can use most "marine" gear oil, except for type "C" which is designed for OMC hydro-electric shift models..."