Transmission wear from the wrong oil
Transmission wear can be from oil contamination or the use of the wrong oil.
These samples show how transmission wear can be reduced simply by using the correct oil.
This example shows the transmission oil of a dump truck that should have been using an oil without sulfur/phosphorous additives. We can see that with the traditional SAE 80W-90 with sulfur/phosphorous EP it had 22 ppm of iron wear. The next two samples, using an oil that meets the CAT spec for TO-4 SAE 50, utilizing zinc/phosphorous additives and friction modifiers, show a reduction of 50% in wear metals.
The second set of samples is of the differential of the same dump truck that used a typical low priced group I SAE 85W-140 GL-5. In the sample of June 2, it had 45 ppm of iron wear. For the next two sample periods it used a group II product that cost 10% more, but reduced the wear metals in half.