I have been curious about the condition of the gearbox since it has been run hard for two years now, if the gear loads are excessive it would show by now so I decided to take an oil sample from the gearbox sump where all of the crap would pool up.
Since I am responsible for, among other things, the hydraulic systems at work I have all the equipment needed to run a test.
With 25ml of oil sampled through 0.8micron paper I could check it with a microscope to see what sort of stuff that got caught.
I was expecting all sorts of crap since I run the oil system without a proper oil filter, but I was pleasantly surprised to find very little metal particles. This indicates that the wear on the gear mesh is acceptable.
The sample paper looks much worse to the naked eye than it does in the microscope, the dullness and occational black dot is most likely from the new tank foam I filled the oil and fuel tanks with. Nothing even close to being large enough to clog up an oil port so it is all ok. I have taken samples from gearboxes with worn cogs and the papers look like they are chromed from all the metal particles on it...
Cheers!
/Anders