300 miles on my rincon since the last oil change. Haven't had to add any oil and it looks like I changed it yesterday. I use Shell Rotella 5w-40. Never had any problems with the tranny, overheating or anything else. I ride 90% trail 10% mud. I normally run 26" Mudlites on c-series rims. I occasionally put the stock wheels and tires on. The Mudlites are heavier and I do notice a power loss.

 

I'll second that one!

 

My Rubicon owners manual is very clear about the type of oil that needs to be used. They specifically state not to use 'energy consrving' oil. I think they mentioned it is because the transmission needs a certain amount of resistance. By using an oil that is too slippery you may in the long term screw up your transmission.

Personally, I intend to stick to Honda's spec's for oil in my quad.