If you remove the oil tank and drain it you will see there are baffles inside that hold the oil around the pump. The sled would have to be very low on oil, upside down for a long time and running before the pump would suck air. That being said, with the aftermarket tanks (plastic ones that come with belt drives) there is much less oil, and NO baffles. I installed a belt drive on my 2014 6000 C-tec and built my own tank from alum. and had no issues with the oil pump ever sucking air from roling the sled to get unstuck. The other part of this is, the oil is so thin (Cat C-tek oil) if you did get some air in the oil line, I think it would self bleed to the top pretty fast when you rolled it back onto the skis.