The dirty fluid he's showing is what came out of the pre-filter side of the cut open filter. That is not indicative of what's circulating through the system. So if you want to be paranoid, at least base it on a proper sample. On both my Kubotas, I have had plenty of chances to see the hydraulic fluid before and after the 50 hour service when changing filters and adding valves, hoses, etc to the hydraulic system. And I see a spurt of fluid every time I disconnect hoses for my rear remotes. The working fluid has always been crystal clear, regardless of the gray gook I saw on the filter magnets during the 50 hour service. What you see inside a filter, on a magnetic ring, or at the bottom of a pan on the plug is not indicative of what's circulating through the system. It just means these countermeasures did their job to remove contaminants from the working fluid. I am all for proactive maintenance, but it should be based on sound reasoning and not paranoia. I have yet to use a hydraulic machine that needs fluid changed at the early equivalent of 50 hours. It's pretty much unheard of. It's darn near impractical for larger machinery with many dozens of gallons of fluid. At 50 hours, these machines will be out in the field and barely even have dirt on their floormats. They aren't going to get hauled in for a full fluid change so early. I think there is an urge to treat some of our tractors like garage-kept homeowner toys, but Kubota's 400 hour hydraulic fluid change is inline with what's typical for tractors and heavy equipment. These *are* tractors. You can bet the maintenance schedule in the owner's manual is based on practical operational experience.
