Getting ready to do the first full Hydraulic fluid change on my 2015 Kubota L4701. It only has a little over 300 hrs, but figure 10 years is long enough on the original fluid. Had the initial 50hr service done (filters swapped and fluid topped off) by me around 125hrs. Original owner hadn't serviced it. My most expensive oil change to date.. Was $600 + for 11 gallons of Super UDT2, 2 hydraulic filters, one engine oil filter and the outer air filter. I'll use a couple gallons of Delvac 15w-40 from the stash for the engine..
Pained me to spend that much on the fluid, but everything I've read says any other fluid will make the HST transmission loud and potentially damage it... Hopefully I'm not doing it again for another 10 years..
In the past I've just ordered everything from Messicks and had it shipped, but shipping on 10 gallons of fluid got me to go to the local dealer. Their prices were 20% + higher than Messicks, but saving the shipping made it pretty much even.