im changing the oil pump and water pump seals also checking the rear diff nut on a friends `09 800 have helped him service it in the past and came across an issue ive not seen on mine when we pulled the throttle body to pull the motor there was oily soot on the engine side of the throttle butterfly but the filter side is clean along with the rest of the intake tract. i pulled the intake itself and the head down around the valves looks fine its just in the TB itself. it has the updated airbox to TB boot and he always uses an oem filter element he also has my version of the grumpymod. engine ran perfect with no smoke( he uses rotella 15w40 like i do) and its never used any oil to speak of. why is there black oily buildup only past the TB butterfly and not before? just wanted another opinion as like i said ive not come across this on my other RZRs. also we checked compression when we serviced it in the spring and it was around 165 on both cylinders and he says it hasnt lost any power or changed in the way its running that he can tell.