I went up to my local Kubota dealership yesterday to purchase oil, hydraulic, and air filters so that I can change them all on my B7500 as I am not sure that this was done prior to me purchasing it. My dealer told me that if the ones on the tractor are all grey then they were not changed at 50 hours. So when I got home that was the first thing that I looked at - and wouldn't you know it they were all grey!!! The tractor now has 97 hours on it and I am very upset that the maintenance apparently was not performed like it should have been. I checked all of the fluids when I first got the tractor and everything was at proper level and all fluids looked very clean and fresh. So this weekend I plan on changing the engine oil, and filter. Can I use 15W40 instead of the recommended 10W30? I have a 16 gallon barrel full of it and would like to utilize that instead of buying other oil. I also plan on changing out the hydraulic filters and air filter. My question is - can i change the hydro filter and pull the screen without draining all the hydro fluid? The fluid looks brand new - very clean. What do you think?