I have a Kubota L3400 with gear shift . I talked with a serviceman in a local Kubota service department about the 50 hour service requirement. He said that changing the UDT in a gear shift is unnecessary at 50 hours. He says that they don't do it. Said they just change the filter. I read on this forum that it should be changed because of all the metal filings, etc. Wouldn't the filter catch all of the debris? Automatic transmissions in most automobiles never require changing the fluid or the filter. My Toyota manual doesn't mention it at all. Only the quick oil change ripoff artists recommend changing it at 30K mile intervals. If they could get away with it, they would recommend it every 3K miles like the engine oil change.I want to do what should be done but it seems extremely wasteful to throw out 10 gallons of perfectly good hydraulic fluid if it is not necessary. Would it be wiser to buy the oil and filter at 50 hours, change the filter only, and save the oil for 400 hours?