Oil & Fuel How important are 300 hour HST oil changes for Kubota B7510 used as a mower?

[rswyan]

Have you ever seen transmission oil turn dark black like engine oil does?

Yes.

It happens when it overheats.

 

[rswyan]

Good grief, you just don't get it do you :yo-yo:

Actually, I'd say he gets it just a little bit better than you.

For one thing, he's not trying to compare apples (engine oil) and oranges (hydraulic fluid) .... and say that conditions/factors that negatively affect one, must be the same identical conditions/factors that negatively affect the other ...

 

[Trials]

Here, you guys answer his question:

Coming up to 600 hours on my Kubota B7510 which runs a 5' belly mower and a 4' bush hog. When I changed the oil and filters at 300 hours there was no evidence whatever of anything but pristine oil and clean drain plugs. Have all of those old HST Kubotas really had their oil changed every 300 hours?

The reason I ask is that I never changed the oil in the running gear of my Toyota 4Runner, and it ran well over 400,000 km without a whimper, notwithstanding Toyota's stern requirements for expensive service. My 4WD Tacoma so far is the same. All I have done is grease them faithfully.

I'm willing to do the maintenance if it does any good, but I think I'll skip that long strainer underneath.

He's a retired English teacher, so he will have no problems understanding what I wrote.

 

[Gary Fowler]

Pray tell, how do you get a sample of HST oil without making a terrible mess. Once the drain plug is pulled to get the sample, just let it drain and replace the oil and filter. Save the cost of a UOA and apply those dollars to a bucket of new hydraulic oil. I do agree that there should be no sulfuric acid forming in hydraulic oil since there is no likely contamination with sulfur like there is in an internal combustion engine.
The biggest issue with HST would be water in the oil which could be easily determined after briefly running the tractor and then checking the oil for milky or foaming conditions. If you had nothing but clear oil and wanted to run it longer, you could feel pretty confident that the oil is still good.

By contrast, changing the oil every 300 or even doubling it to 600 hours shouldn't break the bank to do it.

 

[RjCorazza]

OP: I understand your dilemma. I will be in a similar position when I hit 400h on my new Kubota. I will likely change the filters as specified, and double the HST fluid change hours. This is what I did on my previous L3410 and current zd326 diesel zero turn.
I have sent engine oil samples out in the past, but never considered sampling hydraulic oil. Perhaps I will do that at 800h....

 

[newbury]

Pray tell, how do you get a sample of HST oil without making a terrible mess. <snip>

I admit it might be a terrible, difficult, messy project for some.

I worked the tractor (B7610) for a while to ensure warm hydro fluid.

I turned it off and lifted the seat.

I pulled out the fill plug above the three point.

I stuck a CLEAR aquarium air tube down inside and siphoned out the required amount.

Use a clear tube so you can see it.
Get the fluid warm if not hot so it flows quicker
Wipe off around the plug before pulling it.

The messiest part was the two or three drops of fluid out of the tube after I was done. But I had a full roll of paper towels handy.

 

[rswyan]

Pray tell, how do you get a sample of HST oil without making a terrible mess.

Here's one way:

Fumotoｮ USA | Quick and Easy Engine Oil Drain Valves

Once the drain plug is pulled to get the sample, just let it drain and replace the oil and filter. Save the cost of a UOA and apply those dollars to a bucket of new hydraulic oil.

Likely cost-effective for smaller equipment, with corresponding smaller sump sizes ... bigger stuff, not so much.

I do agree that there should be no sulfuric acid forming in hydraulic oil since there is no likely contamination with sulfur like there is in an internal combustion engine.

Yup.

The biggest issue with HST would be water in the oil which could be easily determined after briefly running the tractor and then checking the oil for milky or foaming conditions. If you had nothing but clear oil and wanted to run it longer, you could feel pretty confident that the oil is still good.

By contrast, changing the oil every 300 or even doubling it to 600 hours shouldn't break the bank to do it.

If one wanted to extend the OCI, probably the absolute minimum I'd recommend is at least visually comparing a sample of the used fluid in a clean, clear container (glass) with a sample of virgin, unused fluid in a similar (identical) container.

And ya might wanna give it 24 hours to see what might settle out.

 

[newbury]

Here's one way:

Fumotoｮ USA | Quick and Easy Engine Oil Drain Valves

I use one of those on my F350 but wouldn't put one on my B7610 for fear of tearing it off in the woods.

Once the drain plug is pulled to get the sample, just let it drain and replace the oil and filter. Save the cost of a UOA and apply those dollars to a bucket of new hydraulic oil.

Likely cost-effective for smaller equipment, with corresponding smaller sump sizes ... bigger stuff, not so much.<snip>

Even on the B an HST and 1 filter runs about $65 from Messicks. Plus the extra hassle of changing the oil versus a simple siphon job.

As I wrote getting an oil sample on the B7610 is real easy for me. I suspect my M4700 will be the same. But the M4700 takes 10 gallons, about 4 times as much.

My fluid from the B7160 came out totally clear.

Like someone said - "doveryai no proveryai"

 

[mikesee]

At $25 a gallon you'd like to think SUDT would still be within specs after 300 hours of use.

 

[MHarryE]

From Caterpillar web site, hydraulic oil color. The hours may seem long but for a hydraulic excavator (hydrostatic track drive, car body swivel), Cat recommends 6,000 hour oil change interval using their Hydo Advanced. Picture is to illustrate color change due to oxidation in normal hydrostatic/hydraulic system application. Yes, hydraulic oil does change color - color change does not have to be engine soot.