f350, I will look for the sheet by International-tnks.
vis sus @ 210F 66.4 sec
vis kin @ 210F 11.98 cst
If anyone can tell me about these numbers I would appreciate it.
They are measuring the actual oil viscosity with two different tests. The first one measures in Saybolt Universal Seconds. The second measures kinematic viscosity and the units are centiStokes. You'll mostly see things in cSt. Based on this chart:
, 12cSt and 66sec are about at the line between 40w and 30w straight engine oil. Now assuming that I found the exact product you were using, the original viscosity should have been over 15 (AMSOIL - Synthetic 5W-40 Premium Diesel Oil (DEO)
, toward the bottom). So it would seem you've got some viscosity breakdown taking place. This might be exactly that shearing the others mentioned.
For the best insight into UOA, you get a virgin oil sample taken and tested and compare it to the used oil. Then test the used oil again at the end of your expected oil life and see what the progression is. Just google for VoA (Virgin Oil Analysis) and the type of oil you have to find if someone else did this for you already.
Basically, with UoA you're watching for some numbers that will increase (iron count, FDRS, FDRL, silicon, copper, tin, fuel dilution) and you don't want to see those numbers increasing rapidly or get too high. Since many of these elements are already in the oil, the VoA numbers are very important. Other numbers like TBN and viscosity will decrease, and the oil is considered "spent" when those numbers drop unacceptably low. To compare two oils, you pretty much have to repeat that whole process and keep operating conditions as similar as possible to compare the trends. Yeah, it's a lot of UoAs to be truly conclusive with this stuff.