OK.....why do you believe you can make an oil for the engine that it better than what a factory can make?  Although thick can help slow down oil burning.....thick isn't always better.  You should stick with something in the 10W-40, 15W-40 or 20W-50 range.....synthetics may have a broader range.  If you make the oil too thick you waste a lot of power just pumping the thick oil, and it drags on the cylinder/piston interface.

I believe gear oil is formulated to lubricate gears....high loads and no pumps or tiny passages - it does it's job by being thick and sticky.  Gear oil probably doesn't have any detergents to help combat the combustion byproducts that get into the oil......I really don't think it would be good for use inside an engine.

Kris01 wrote on 11/06/15 at 18:43:19:


No, that's what I run in big air cooled bikes (Shovelhead or older) in the summer. The Slopokis get 15W40 or 20W50... Can't find good heavy weights anymore, not even HD dealerships carry 60 or 70 around here. And as tiny as Savage oil passages are, going over 50 would probably frag the top end anyway.