My Honda small service book says to use SAE80 Hypoid oil for servicing the shaft final drive differential on my bike. I have found Mineral, Semi, and Full in SAE80 where it mentions Hypoid and Differential use. The Honda service book just says SAE80 Hypoid.
Based on what I used in my mini and reading about ideally the gearbox should use mineral, but the engine should use full, I guess mineral SAE80 would be best for a differential? I dont know how much it really matters!!
Cheers!