On our first Spyder, I used Royal Purple 10W40 Automotive Synthetic, starting at 3000 miles. I got a little flack from the "pros" that my warranty would be voided, transmission start slipping, etc. None of that happened. In fact, after 43,000 miles when I traded it for the RT, the tech checked the valves and found them all to be within tolerance. That was the first and only time they had been looked at. So, the RT is using the same oil. The only thing I worry about is getting enough time to ride like I would like to.