You want to talk about shearing, grinding and pounding, I have an RC51 that has a completely gear driven, flat tappet valve train. I use Shell Rotella T in there, in my XRL, my XRR, my lawn mower, my snow blower, and anyone else who's oil I change. ZERO issues, hot, cold, dyno tuning, 10,000 RPM shifts on my RC. The diesel oils have much more additives including ZDDP, which regular motor oils and motorcycle oils have less. I need this for my flat tappet cams. This is the first oil debate I've chimed in on, you can run whatever you want in your bike, the main thing is to change it often, check it often, and never use ANY oil that has "energy conserving" in the JASO (Japanese Automotive Standards Association) printed on the bottle.
Just so I understand: JASO MA/MA2 is correct, but if it has "energy conserving" stay away from that particular brand?