In a common sump tractor it outperforms engine oil in all regards including price.
Dan
Been thinking about your comment - much appreciated. On the next trip to town and I was at the farm store I went through the lube isle and there were no pales of synthetic UTF, go figure. I was about resolved to just finish with petro UTF but my eyes caught an item on the shelf above where they had gallon and quarts of Amsoil Syn UTF so I bought a gallon to finish the lube change so all synthetic now. Anyway, the following week I had a long drive to a neighbor's place and back home up a serious grade with the synthetic (60% Mobile1 40% Amsoil UTF) in the gearbox. Between the needed change out of the lube and the change over to synthetic its was absolutely noticeable. The 'growling' in 2nd gear is about half and the in reverse it is mostly gone but of course that is always crawling speed. Anyway, an interesting experiment as I had some Mobile1 of a weight that I wasn't going to use anymore and this was a good test case. It'll be a long time before another fluid change because it never happens by hours but by condensation....
Another thing I've been pondering since thisexperiment: for years and years I have used Marvel oil for everything from cutting fluid to penetrant to fuel additive (sparingly). Plus it smells good

I have seen where people insist that xmission fluid is a good penetrant/additive and got to thinking of just quitting the Marvel thing and using petro UTF for all the above.
Ironically, with this subject, when I changed out the xmission/hyd fluid in the big loader/BH/hyd it specified motor oil, not UTF. Caught me off guard as I had purchased 5 pails of UTF for the project so I had to go get different lube and now have plenty of petro UTF.... For the big machine and the toy machine I monitor closely. I don't pull samples for testing from the Toy (Kubota) but its a grudge thing that is curious:
How long will this critter keep going and doing so well? It runs smooth but is obviously lacking some compression and keeps mosquitos away under load. The only thng lacking is the need to refresh wiring and I will do that when its not 100f in the shade.