2001 Rubicon has recently been using oil. There is oil in the airbox so we cleaned it out. Ran the quad for 10 miles and you can already see that the oil level is dropping again and there is oil in the airbox. We can only top it out at 44 mph compared to about 54 mph before. Do you think that it could be a cracked ring and the pressure is pushing oil into the airbox somehow? There is a little oil out the exhaust, but that is probably coming from what's in the airbox. Thanks, this is for a friend of mine who doesn't have internet access.

 

Only one way to find out; do a leak down. Doesn't sound good though.
If your sure the case is not over filled, it sounds like a ring/bore problem.