Amsoil now has a 10w-30 for ATV's for those that really believe in only running the recommended weights.
AMSOIL Synthetic 10W-30 Motorcycle Oil (MCT) is a premium oil designed for those who demand the absolute best lubrication for their motorcycles and ATV's. AMSOIL MCT is the result of extensive research, and it is specially formulated to excel in all areas unique to motorcycles, including high engine RPM, wet clutch lubrication, extreme pressure regions of gears and rust common to short drives and storage.
AMSOIL MCT is multi-functional and fulfills the requirements of both domestic and foreign motorcycles. It outperforms other conventional and synthetic motorcycle oils.
Filter number for a 2007/8 Raptor 700 is AFF 24935 (Wix).
For more information and test results visit
http://www.amsoil.com/storefront/mct.aspxI'm sticking with the 10-40 as I've been running it for 5 years now and really don't see a reason to switch