I agree with you Mark, but keep in mind that for many of us there is a substantial price difference. What you pay for Rotella T6 synthetic is less than what Canadians pay for conventional Rotella T. And T6 is around $50 for a jug on this side of the boarder, and our currencies are roughly on par!
We need to chip in and all ride down and stay at Scorpio's place. On the way home we can each declare $800 worth of 5 gal. pails of T6!
My comment earlier was about the viscosity ratings, not one brand -vs- another or synthetic -vs- dino. My understanding has always been that a multi grade oil performs per the first number when cold. That's why we put 5w-30 in our cars at 1,300 asl in the winter. Otherwise, on a real cold morning, the battery doesn't have enough juice to turn the engine over if it has 10w-30.
And, it performs per the second number at 210/100 so we use 10w-40 in the summer so the oil is not too thin on a hot day going up-hill with the A/C blasting.
I therefore think of a 10W-40 as a 10 weight oil that will not thin more than a 40 weight would when hot.
I agree that our bikes seem to like 50 oil in the hot summer, but in the spring and fall, my battery and starter could barely churn through the thick 15 (cold weight) oil. 5w-40 would be perfect in the spring and fall, and 10w-50 (if you can find it/if they make it) would be ideal in the summer.
The 3rd point was based on the comment that sometimes a pure synthetic in an old engine can eliminate the residual sealing of years of dino oil and actually reveal engine seals that need replacing because they now leak. If you
WANT to find seals and gaskets that need replacing, then I suppose this side-affect (if it's true) would be a great diagnostic tool.
But be careful what you wish for if you are going to come running back to the Forum with a
"boo-hoo, I have oil leaks - HELP!" thread.