Thanks for the reply.
I happen to specialize in sand and investment casting engineering/design for potable water systems. I'm 100% certain the speculation as to why Kioti states to change these two massive hydraulic filters is not due to any sort of manufacturing residue. These systems are far to delicate and tightly toleranced to allow such residue to ever circulate.
I saved the 2 filters but did not bring them home. I'll eventually cut them open to prove my point.
One filter might be under slight pressure and the other a slight vacuum may be both see pressure. But I'm also 100% certain neither of these are high pressure filters in terms of being special or unlike other standard filters like the filters with spanner wrench fittings and thick walls. Not only are they missing features for tightening and securing, but they are thin metal like all the rest. And most importantly, much too large to hold any significant pressure.
So really, we have no idea what's behind Kioti's specs and I still find it incredibly odd there are two filters for the same fluid.
What I really want to get out there is that when removing the transmission filter 2.5 gallons of fluid dropped. This really pissed me off because I was not prepared for it. Not prepared for that much to come out...nor enough to refill the system. Had I known this ahead of time, I would not have changed either filter until 200 hours when the oil and oil filter are called to be replaces.
I know the HST filter of the DKse tractors see 255psi, though the HST itself sees around 5000psi. The DKse's HST filter has a much thicker shell than the one you are showing for the ck2610 HST.
But regardless of pressure, the reason for two filters is to provide better protection of the HST by itself, as the filter is placed just before entry to the HST. After that first suction filter there are many places the oil must travel. Many places it could pick up debris before it finds its way to the HST. An example would be the power steering unit (in the DKse series). If the power steering pump were to fail, the next stop for the oil is the HST. Without the dedicated HST filter, the HST would also be destroyed. For the CK tractor, it could be a charge pump failure that would destroy the HST, if not for the dedicated HST filter. After a power steering pump, or charge pump failure, the suction filter can do nothing to save the HST.
Speaking about first oil changes, most folks who carry out a lot of heavy machinery maintenance can tell you how trashy oil can look at the first 50 hours of any new equipment. I know my kiotis oil looked opaque in color, with a teaspoon worth of grit mixed in on that first 50 hour change. Its never look that bad since. Most likely was sitting in the bottom of the sump, having been flushed out of every port and too heavy to be sucked up. But beyond the items that have fallen out of suspension, there are elements in the oil that are not filtered out, that can be just as bad for lubricated equipment. Anything less than 11 micron, (or whatever filter is being used, this is the DKse filter mesh) will continue to build within the oil as the hours go by. Same goes for any foreign chemicals that can get into the oil. The quality of oil is far more than a particulate count.
Its great to see you mention opening up your filters, I would encourage anyone to do the same. People can learn a lot about their equipment this way. If you have easy access to a lathe, it makes the job very quick, clean, and painless. But a hacksaw works fine. I was please to find out that kioti filters were built well on the inside with metal end caps and bypass valves, but I think many would be shocked at the trash they may find that it's picked up. Lots of metal and grit, the media completely gray from metal powder. Same goes for engines, you wouldn't believe the amount of metal powder that gathers on a magnetic drain plug in a freshly rebuilt iron block engine from all of the new parts mating together. The entire transmission of a tractor is no different. The last thing you want, is a filter full and bypassing on the original oil. A filter change at 50 hours can help prevent this. After the initial 50 hour change or so, the filters are never as compromised, and look much better internally.
I know all equipment and automotive companies make a lot of money on service, but I don't think its a waste for the consumer to do the 50hr. Especially when there are cheaper, and possibly even better brands, like Wix you have mentioned, or Donaldson out there with x-references to factory filters.
But there are far worse things one can do to equipment than skip the first 50hr filter/oil change. I just like rambling on about the subject of operation and maintenance.
I understand your frustration with loosing all that oil too, as a proper manual could have prevented that.
There is no acceptable excuse for the crap manuals provided by Daedong USA.
