I just checked the manual, page 116 and it specifies synthetic or sythetic blend at 10w/40 or 15w/50 and mentions Mobil 1 Racing 4T (MC specific) as a prefered mix. Since that mixture isn't available state side I would go with the Mobil 1 MX4T 10W-40. Here's the data sheet: http://www.mobil.com/USA-English/Lub...cycle_Oils.asp