I've been reading here and there about different ATV oils for a couple hours. Today I changed the oil in my 2001 Honda 300EX sport quad from Valvoline to Honda GN4 that I got from work. The clutch grabs better and the gearbox seems to shift smoother. But, even with my discount, it's still spendy. If I'm reading right, a lot of folks have used HDEO's in wet clutch applications for a long time. I don't recall the HDEO's having the JASO MA labeling though....so, are they still ok to use? I change my oil frequently, so cost is an issue. Also....if Rotella products can be used, how would the T6 5W-40 do in this machine? Every other small engine I use it in runs cooler and smoother....something I'd like for the 300EX as it gets quite hot on the trails. I'm also open to opinions on other oils like Maxima, Mobil1 4T, Castrol etc. My 300EX appears to be all original, never opened up, and has the original clutch.