My manual and several members on this forum say change the hydraulic oil every 300 hours. My tractor is approaching 300 hours so I am planning to change it. What actually happens to the oil. Does it degrade, or get dirty, or something else? Also, what do you do (legally) with the old oil. Thanks, guys!
Oil & Fuel WHAT HAPPENS TO HYDRAULIC OIL?
- Thread starter GeneSimm7
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Rock knocker
Veteran Member
It gets dirty from mechanical wear, picks up some atmospheric water and dust, and degrades thru heat and evaporation of some distallates.
I mix mine with enough used motoer oil to fool any hyper alert employee at the auto parts store, and recycle it there. I actually hink one could recycle it without any effort to hide its real identity because it is a simple distallate or syn-oil. Recycling really only has issues with motor oil polluted with gasoline or brake fluid
Gordon Gould
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When we recycle oil here in the county waste management facility all the oil goes in the same storage tank. Any kind of oil or hydraulic fluid. The only thing they ask is if there is any anti-freeze in it. If so they have a different tank for it.
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ericm979
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Hydraulic oil is regular oil with somewhat different additives than motor oil. Some hydraulic systems actually use motor oil. Used hydraulic oil is cleaner than used motor oil because it does not contain combustion byproducts. Recycle it where you would recycle motor oil. The county recycling here takes it with no problem.
Hydraulic oil will wear due to heat (though it does not get a hot as motor oil in an engine). It will also wear due to shear action. Oil molecules are fairly long and as they get put under pressure they sometimes break into smaller molecules. Those have a lower viscosity than the original molecules, so the oil slowly gets thinner. The hydraulic pressure pump(s), gears in the transmission and rear end, and the HST if your tractor has one will all wear the oil.
Hydraulic oil will wear due to heat (though it does not get a hot as motor oil in an engine). It will also wear due to shear action. Oil molecules are fairly long and as they get put under pressure they sometimes break into smaller molecules. Those have a lower viscosity than the original molecules, so the oil slowly gets thinner. The hydraulic pressure pump(s), gears in the transmission and rear end, and the HST if your tractor has one will all wear the oil.
MHarryE
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If the tractor doesn’t allow hydraulic oil to get hot enough for oxidation, cleanliness is the limiting factor. At Caterpillar our current standard is 2,000 hours or 4,000 hours if you sample the oil every thousand hours to make sure it’s clean, not oxidized, and minimal water. That is for hydraulic excavators where, like their name, virtually everything other than fan, alternator, and air conditioning is hydraulic. Why tractors need such frequent changes I don’t know unless the gear teeth they also lubricate put too much crud into the system for their filtration to handle.
davek78063
Member
Because tractor mfg like to sell hydraulic fluid and services
All kidding aside, it does seem like cheap insurance from my perspective, though I don't actually know if it is just wasting oil and money.
4570Man
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Because tractor mfg like to sell hydraulic fluid and services
I think there’s a lot of truth to that. And it’s not very cheap if you’re using Kubota SUD-2 fluid.
CalG
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The only reasons to replace Hydraulic fluids is to renew the additives such as anti foaming and corrosion control,
AND to expunge accumulated water that has been introduced into the system though many mechanisms. Temperature changes and vent tubes being predominant.
The "fluid" would likely remain perfectly useful if not for these secondary issues.
Analysis would prove the technical aspects, but a fluid change is less costly.
Send me you drained fluid, I'll burn it!
AND to expunge accumulated water that has been introduced into the system though many mechanisms. Temperature changes and vent tubes being predominant.
The "fluid" would likely remain perfectly useful if not for these secondary issues.
Analysis would prove the technical aspects, but a fluid change is less costly.
Send me you drained fluid, I'll burn it!
oosik
Epic Contributor
Speak to me of costs - almost 17 gallons of hydraulic fluid for a change in my M6040. I take all used oil - engine, gear, hydraulic in to the Kubota dealer - the service dept has a waste oil furnace.
By-the-way - Gene, what sort of tractor do you have that recommends hydraulic oil change at 300 hours. My M6040 says every 600 hours.
By-the-way - Gene, what sort of tractor do you have that recommends hydraulic oil change at 300 hours. My M6040 says every 600 hours.
