Hydraulic fluid break down

[nascamp]

I have a Kubota L 39 does the fluid break down and if so after
how long ?

 

[ROUSTABOUT]

I don't think it ever brèaks down, it just gets contaminated. So keep it clean with filters. Keep the water out. I give this opinion based on experience and schooling.

 

[rScotty]

I have a Kubota L 39 does the fluid break down and if so after
how long ?

What a good question! I'm curious myself, and don't know the answer. That's in spite of having been doing mechanical things for a long time - both professionally and as a hobby.

I'm a reader. Every manual and textbook gives a time and use-based schedule for changing fluids. The implication is that filtering is only useful for gross debris, that fluids themselves have a lifespan, and therefore fluids must be replaced regularly & no questions allowed.

The problem with the periodic fluid replacement philosophy is that I haven't found any research to support it. Nothing in print or experience that convinces me me that replacement it is based on anything other than opinion. I'd like to believe in replacing fluids, but little to nothing seems to have been studied about fluid aging or questioning the rationale for totally replacing fluids. It sounds like common sense, but as far as I can tell, the supporting evidence is missing.

There is a huge petroleum industry based on replacing fluids, and no industry at all based on ultra-filtering, refurbishing, and reusing old fluids. Technically, rebuilding an old fluid to return it to original specs should be a simple process. I'm surprised it isn't done. All the tools and methods already exist.

Even without replacement of fluids, in my extensive experience as a farm kid, mechanic, shop owner, and mechanical engineer .... I have never seen a failure I could put my finger on and say, "This was due to old fluids."
I've seen plenty of machinery that never had the fluid changed at all, just more added until sludge on the bottom of the sump was built up inches thick. That used to be common. And not once can I say with certainty that the wear inside was due to old fluids.

rScotty

 

[nyone]

Dosnt your manual have a service interval?

 

[jonsstihl]

I have seen the effects of old fluid and it is not pretty. but I think other factors come into play. the stuff I have seen is mushrooms in the oil and the oil turns into grease and has hardened deposits in it. But what I have personally seen comes from the aviation industry and it is due to removal of an engine due to a problem and the broken engine is left on a shelf until someone gets sick of looking at it and sends it in to get repaired. we are talking years of no use at all stored in an uncontrolled environment.

I think as long as you get the oil up to operating temp every once in a while It can last a lot longer than the oil companies are telling us.

 

[oldnslo]

Typically biggest killer of hydraulic oil is heat, excessive heat. A lot of systems today run 180 - 210 degrees F which most oils will handle. Get 40 - 50 degrees hotter and some additives, base stocks, etc can start breaking down.

There are companies that will do comprehensive oil analysis and tell you if oil is still is acceptable use range or if it is starting to break down.

 

[MapleLeafFarmer]

In my retirement I look for things to do.
I have taken a couple of lubricant classes and both times we were told it can break down in as little as a year if handled poorly.
But in sealed containers lasts almost indefinitely except take care that the newer more expensive stuff can settle out as the newer / bigger buck fluids tend to have more additives. (like paint settling in cans the heavier stuff goes to the bottom)
Depends how stored and how used is what they told us.

Biggest culprits were told that lowers life is:
- exposure to air
- exposure to water
- overheating
- contamination of metal and other particles


edit: they gave us the same story for engine oil and rad. fluid also.