Does a stern drive have to use marine grade gear oil?

If the V-drive or Differential is subject to being under water, the answer is Yes!





Conventional gear oil goes foamy when mixed with water, but marine rated gear oil doesn't, it sticks to the gears and bearings providing the lubrication they need.Does a stern drive have to use marine grade gear oil?
I'm not sure what you are asking, but in general, you should use the oil recommended by the manufacturer. For years, Volvo, used the same oil used in the engine, in the drive. OMC and Mercury had special oils for some of their drives. In the last few years there are more synthetic oils used in drives. The cost of non-marine oils is only slightly less than the marine stuff, so use the marine gear oils.Does a stern drive have to use marine grade gear oil?
I have very good experience with Mallory marine gear oil, Green sticky syrup like synthetic oil lube, it takes some longer to fill the gearcase though.
just diff oil will do buddy no water gets in to the leg if it does have water in the leg its only water pick up for the motor