Re: 1969 Johnson 55HP Electric Shift--lower unit gear lube
The only lube you want to stay away from is thick hypoid oil. It makes the gearcase shift sluggishly and somethines prevents full engagement. Most synthetics work well, and Premium Blend is certainly fine. Type C is the aftermarket name for Premium Blend and is fine too.
The difference between your kind of electric shift and previous types is that yours shifts hydraulically with electric solenoids operating valves. Older electric shifts used electromagnets to pull a spring wrapped around the gear to constrict and grab on. Those needed thin lubes to squeeze out of the springs, plus fewer anti-friction components to allow enough friction between the gear and spring to allow it to hold. Yours (mine too) doesn't need the latter property. That's why I use synthetic in mine.
Don't get Mercury's Premium Blend. It's a thick gearlube and not the same as Johnnyrude's Premium Blend.
