Dirt, your experience with the Amsoil MCV 20W50 has been much better than my experience with the Amsoil MCT 10W40. In my bike, the Amsoil 10W40 dropped to the middle of the 30 weight range by the end of the oil interval, which happened to be in the winter so technically even a 30 weight was still within the temp chart guidelines in the manual. There was some debate that maybe the lower viscosity was from fuel not from shear, but the lab noted TR for "trace" with regard to fuel so I have to think from that it was [gear] shear and not fuel. Also, my aluminum reading was a little high on the Amsoil 10W40, although that could be attributable to being a new engine less than a year old at the time. I do beleive Amsoil to be a very shear resistant oil, if not one of the most resistant to shear that one can find, up there with Spectro, Silkolene, and Motul. And given that the oil change was preceeded by a two hour highway ride with very limited city traffic operation right before draining, it further indicates fuel dilution would not be the likely cause of the viscosity drop that was found by the analysis.
So it is that experience with one the most shear stable oils on the market going from a 40 to a 30 that has brought me to the conclusion, along with a recommendation by the Ducati Master Technician at my dealership, to adhere to 15W50 from now on so that when not if it shears, it will still be a 40 weight (most likely) by the end of the service interval. I should note that the oil run referred to above was not the full Ducati 7500 (miles) it was about 4500.
You're certainly on top of it.
Gear boxes are tough on the oil.
So is the engine with it being an L-Twin
Regarding the fuel dilution.
I really don't understand what trace is
My lab reports the actual amount they detect.
But anything above say 2.5% may well be deemed to be too much(depending on the lab and application) they will report that it indicates a problem of some description.
Other labs will deem 3% to be a reasonable threshold.
Having said that 0.5 % extra over and above long term averages, can potentially make a world of difference in the oil's viscosity.
Sometimes the negative effects on the oil are from the aromatics in the fuel.
The solvent effects of the fuel alone can significantly attack the oil molecules and oxidise the oil leading to its demise.
Then when you take it for a long run to burn off/evaporate the fuel out of the oil, it doesn't show up as being problematic fuel dilution levels in the UOA.
But the damage has already been done long before, by the fuel that's previously loaded up in the oil thousands of miles ago.
In all honesty I'm not certain of any of the other oil brands you have mentioned there.
I revert to the Amsoil Motorcycle Oil White Paper.
Only a couple of oils rate very well overall, and there can be a disconnect between the performance of one brands 10w-40 grade and their 20w-50 grade.
That's why like yourself, I validate the oils performance with the UOA's at the time of the oil change to keep a close eye on things.
Over time, It provides a baseline for what's normal for that machine.
Then anything that's a significant spike can maybe point the way to trouble, or verify a problem you know that is current or has been rectified earlier.
With the MCV, it starts out as a 20w-50 and effectively ends up a 15w-50 in all my applications. And the wear metals are consistently low.
With loads of ZDDP left in reserve, and also TBN for laughs.
So I'm very happy with that
I think I'm getting good value
It's not that I don't look around for alternatives though.
Everything is up for constant review.
But I still keep coming back to the MCV, as it ticks all the boxes in every respect.