Converted a 2008 YZ450f for street use and it's using a lot of oil. Never burned oil before and it doesn't smoke. No leaks. I've been riding it around town and the oil level stays normal but I ran it on the highway for about 70 miles at about 6500 RPM and the dipstick barely touched the oil afterwards. Again, it doesn't smoke, runs great, and there are no leaks. Any ideas? No excessive oil blowing out of the breather tube either. I'm running Rotella T6 BTW.