My nephew will turn 18 in July, he just bought a nice 2001 Ranger 3.0 5 speed with 96k miles. I offered to help him go through all the fluids and fix it up little by little. He has the 7.5 open rear end, I drained out what I suppose was the factory fill and sealed it back up with a Fel Pro gasket and some Supertech 80W90 conventional. He drives it easy, doesnt run it hard, and has a 12 mile round trip drive back and forth to school every day. Are the Supertech gear oils decent, and how long should he go before we change it again? I was thinking every 50k but I figured I’d ask here first.