Dave,
Rotella oils have been known for decades among experienced bikers as one of the very best motorcycle oils out there. Go to any bike list and search for Rotella and you will find their oil discussions. Ditto for oil discussion lists like BobIsTheOilGuy.
This is T6, same derivation base oil as Shell Helix, the oil that goes into the Ferarri formula 1 race cars. Our T6 has gone 300,000+ miles in a big truck engine for durability and has gone racing with every brand of motorcycle out there for our style of stress testing. It is very very high temp stable.
Rotella has a base oil construction and oil additive packages that go FAR beyond car oils (and most of the "motorcycle oils" from the car oil manufacturers).
Rotella did us the kindness of testing their 15w40 dino oil and their 5w-40 synthetic against the JASO motorcycle standard and they passed neatly and cleanly on the first pass. It was done a courtesy to the biker world as Rotella is intended for use in huge diesel engines and our yearly sales are peanuts compared to over the road diesel sales.
So, I now avoid questions like yours by saying "Huh?" "It's a bike oil, sez so right on the jug. Why shouldn't be good for bikes?"
But if you want to review the old list oil wars, we have gone into the base oil structure, the manufacturing processes and the additive package systems. Rotella oil is really quite good stuff to be selling so inexpensively.
Much of that low price comes from the fact it is normally sold by the full pallet to truckers who use 15-20 gallons at a shot.
But we buy ours by the single gallon at Walmart.