Originally Posted by Bonz
M1 15W50 far right column in this thread from 2014... shared sump engine ZRX1200, just over 4,000 miles. Sheared down a good bit.
https://www.bobistheoilguy.com/foru...1200-mobil-1-10w40-4t-racing#Post4865603
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Good post and interesting too.
The 15/50 sheared down a good bit but in your case to a 40, if your good with a 40 weight oil as you have used 10 and 15/40 in your other OCIs, the 15/50 gave you great wear numbers. To me, in a quick glance based on mileage, they look like the best wear numbers. Without changing the subject, when talking 50 to 40 or 40 to 30 types of shearing Im not as concerned as actual wear numbers, because its not only about shearing, its about film strength and I think why modern automobiles/trucks can now go down to 0/20 oils, unheard of decades ago.,.
So it ended up as a 40 but your good with 40 anyway.
I was never a proponent of the M1 15/50 but I can clearly see in cases where a API "S" oil can be used the M1 maybe hard to beat value wise. Heck I would even be tempted to use it for fun and send it off to Blackstone if I didnt need a "C" rated and even then, maybe if I wasnt in such a hot climate.
Oils are far more complicated then the EXTREMELY few components that are tested for in a lab when we do VOAs and UOAs.
Even though UOAs are fun ... (and even I am waiting for my UOA from Blackstone that I sent out last Saturday, still not done. on a C rated semi syn 15/50 which I have been using almost since the bike was new.) its impossible to predict actual engine wear based on looking at the reports and how much an oil might have sheared but in a shared sump, it s**cks when oil shears down and shifting gets notchy, been there, done that on past metrics I owned. I always found conventional oils provided best shifting on those bikes,