One reason the Rubicon takes more oil is because it does so much with it. The SP just uses the oil in the engine. The Rubi uses the oil for engine lube, tranny lube, plus the oil is used in the hydro unit of the auto tranny. The more oil the better, but more is needed the harder you work it. That's why the manual shift Xpeditions take over a gallon - one oil for engine, tranny, & clutch.
farmr

 

Rig,

The SP and Ruby are both great quads. Most noticable difference is ride quality, the SP has a softer seat and the suspension really soaks up the bumps. My Ruby came from the dealer with the tire at 5 psi. The owners manual suggests 3.6 psi so I made the change and the ride improved noticably. The Ruby does feel better than the SP at higher speeds.

I haven't figured out the downside to Honda's new 4 wheel drive system. The steering is light, all four wheels pull through the mud. I've climbed with one front wheel totally off the ground and the front wheel with contact was the one spinning, not the one in the air. All in all, it seems like the perfect compromise to me.

Other than that, there's just little things, like having a gas gauge on the Ruby and the cool digital instramentation. Oh yeah, and the engine braking... WOW!...