Hi everyone.. I'm new to excavators and this forum. I just purchased a pretty good shape komatsu pc75uu with 3800 hrs. I already changed the engine oil with filter and now I need to change hydraulic oil. I have the shop and parts books and it says to use engine oil for replacing oil in the hydraulic system. That's fine and dandy but I'm not real sure of what oil I should put in it. I used Rotella 15w40 for the engine. Is this oil ok to use in the hydraulics or should I run a 30 weight instead. Is it good or bad to maybe run synthetic in it vs conventional? Also while I was running it in the dirt the other day the right side track kept popping every now and then when making slight turns. It would clank and make a little bit of a binding noise then it would snap back into place. Is it may be the bottom rollers are worn? Guy I bought it from rebuilt the tensioners and the tracks seem to have the correct tension. It's not like their to loose or anything. Anyways any help with these subjects would be greatly appreciated since I've never work on an excavator before. Thank you in advance
I have a pair of 75UU's and 15-40 is the engine oil I use, NAPA universal hydraulic oil is what we use for hydraulic oil. Have never had any problems with these choices.
pc75uu-2 Ok.. appreciate the response. I thought it was kind of weird that the book says to run engine oil in the hydraulics and it seems like their are plenty of mixed reviews on the topic. Some people say they do and some people say they dont. Have you ever had any track binding going on with either of your machines assuming they are steel tracks?
Typically hydraulics if it says to use engine oil. you would be safe with 10w30 or 0w40. pending how cold your weather gets. if you run 15w40 and its cold outside, you could cause damage in your hydraulic system and your system will be sluggish. if temperature is a non issues. you can essentially run any engine oil. 15w all the way down to 0w
I have replaced the tracks on each machine, but they were rubber,not steel. The steel rails were wore out on both of mine when they were replaced, they did bind up and would also come off easy due to being wore out. This could be your problem also or they may be just loose. Another problem can be the pins may be seized.
https://vimeo.com/116155821 PC75UU