I don't get it..??

I put 10w30 in mine because the factory recomends it and they have engineers that make a sh*t load of money that figure out if you need gear oil or motor oil. they design the bearings and busshing to use a thinner motor oil, not a gear oil. it may "feel" better but your really not lubricating your bearing correctly. BUT this is on realy realy small scale! I run the 10w30 becuase it seem less slipery to hold the clutch bettter. you can put ATF in there too!
Mark