If you're referring to gear lube viscosity, it's measured on a different scale! Sprintman is talking about a real motor oil viscosity.
Sprintman, I thought that it was 25W70, but 40W70...that's a real-man's oil.
I agree...I think these engines that spin to like 9-10k rpm's would shred on a 5-20/30. That's why motorcycles spec. oil with more cojones as well. So all you who think an OHC needs a 'thinner' oil...guess again...