Factory specs are telling me to put 80w90 oil in my 350 warrior I've never heard of such thick oil answer someone?

Factory specs are telling me to put 80w90 oil in my 350 warrior I've never heard of such thick oil answer someone?
What you are looking for is EP80W/90 MANUAL TRANSMISSION FLUID. It is manufactured by Castrol, one of its PROTECTOR SERIES Oils. Castrol Manual Transmission Fluid EP80W/90 is manufactured for EXTREME PRESSURE engines, such as your 350 Warrior.