Hey friend, was reading threw here an saw ur issues with the th 460, im very familiar with him, I worked at a cat dealor for bout 7 yrs, if the cat guys are telling you that you have dirty oil in ur systems due to lack of serviceing properly, an you say you keep changing ur hyd filters out an its not helping ur problems due to the whole hyd system,,,,now I nay be wrong but I don't think that the trains. fluid an hyd. fluid are in the same system as each other,,, I remember that the trains. has its own dipstich there behind the batteries, but either way it ur cat guys are telling you that ur oil is dirty WHY HAVENT THEY MENTIONED PUTTING UR MACHINE ON THE FILTER CART don't mean to sound like im yelling at ya but I worked at cat for yrs an they use to run the cart on machines all the time to filter the oils to get the particle count down, the paticle count is the dust like trash in the oil that ya cant see with just ur eyes alone, the filter cart is amazeing ,, its locks like the big propane tank out in ur back yard that hase big filters in it to cat the particles an returns cleaner oil back into ur system, it has hoses that ties into ur machine while ur machine sits there an idles for few hrs then the tech takes an oil sample an runs it threw a machine an it tests cleanliness,,,,,,just like a DNA lab does,,,, it ll even tell ya if you have a lot of a certain type metal in the oil that's not suppose to be there (basicly tells you if ya have bearing wear going on or if maybe coolant is starting to leak into that particular system) kinda help with preventive down the road break down, but back to the filter cart each machine has its on standards to meet for cleanliness an after running the cart for few hrs an he checks the micron readings if its now in spces he changes the filter cart filters an tractor filters an runs it again, sometimes a all day thing but it will eventualy get the oil clean. as the cat guys bout the cart. they have to have one for there warranty reasons an to save there own buts down the road.