Hydraulic Oil Replacement

   / Hydraulic Oil Replacement #1  

tlb13057

New member
Joined
Aug 27, 2007
Messages
15
Location
near Austin, TX
Tractor
PT425 (2003)
When is it time to replace hydraulic oil in a pt425? Tractor is 10 years old and never changed hydraulic oil, but replace hydraulic oil filter regularly. Oil is same color as the day it was bought but does not smell like fresh oil any more. Is this a problem? All hydraulics seem to work fine, no leaks.

If changing the oil, do all the lines/cylinders need to be bled, and how would this be done? What is the recommended weight (for hot climate) for the hydraulic oil? I have read 10W40 or 5W40 on posts.

Thanks,
-Tim
 
   / Hydraulic Oil Replacement #2  
The range of comments you will get range from now to never. Oil tends to break down over time and if you have not had a major hose failure in my opinion it is probably time. I hear going synth may be the best for a warm climate, tends to not build up as much friction so it is cooler. Hydraulic fluid is also mentioned a lot but in the end most people I talk to just use 5 gallon drums of 10-40. I personally suffer from hose ruptures enough that I keep a cheap case of chevron 1040 from Costco on hand. Nothing fancy for me but I spill a lot of oil on my machine.

Oh rotatella is spoken highly of.

Draining hoses ishard to do. I wouldn't worry about it unless you had water.

Finally 10 years on hoses in warm weather means I would check them all over and replace any worn, stiff or outer cover broken.
 
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   / Hydraulic Oil Replacement #3  
I suggest you change it. Motor oil used in hydraulic applications is subjected to constant "shear" as it goes through pumps and motors, and is by-passed and forced through tiny orifices. It tends to break down the molecular structure of the oil, which isn't visible to the naked eye, and would only show up in an oil analysis. There's really no way of knowing exactly when it needs changed, short of paying to have an oil analysis done...

For a predominantly warm climate, where you don't have to worry about cold weather starting, I would certainly recommend 15w-50 instead of 10w-40. The thicker the oil (the higher the viscosity), the more it will resist shearing and by-passing, and the more hydraulic power it will transfer -- within reason of course, you don't want to try pumping gear oil through a hydraulic system.

IMO, you'd likely notice the difference in power transferred to the wheels, for example, after a fresh oil change -- especially if you step up to the 15w-50. I certainly did, as did others who changed to Mobil 1 15w50, for example...

The biggest reason to change it is that the oil is absolutely full of suspended metal particles that are small enough to pass through the 10 micron filter on the PT hydraulic system -- not to mention the fact that that filter doesn't filter all the oil that is going through the pumps all the time. Much of the oil that goes through the pumps (for example PTO pump when not using the PTO) gets dumped right back into the reservoir without going through the filter.

When you get the used oil out, you'll be able to see these tiny suspended particles of metal reflect light and you'll likely be surprised how much metal was floating around in there. When I changed the oil in mine, I put the used oil right back into the one gallon jugs the new oil came in. A few months later, I looked at it, and there was a grey sludge of metal particles that had settled out of the oil on the bottom of the oil jugs that was 1/32 - 1/16 inch thick, I'm guessing. And this was from a machine with about 300 hours on it at the time...

My 2 cents, your mileage may vary...
 
   / Hydraulic Oil Replacement #4  
Another issue is water - many variables (local climate, tractor use/storage...) affect how much water ends up in the hyd. system.

Part of the sumps jobs is to collect water, as well as metal junk. You can't tell, by looking at the dipstick - on mine, the oil looked nice and clear on the stick - once I drained the sump, the oil looked pretty disgusting.

(If you've ever changed the oil on a modern Briggs powered push lawn mower, you would have seen this same effect. The oil can look great on the stick, but what comes out of the sump more like tar.)

Rgds, D.
 
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   / Hydraulic Oil Replacement
  • Thread Starter
#5  
Thanks for all the feedback. It will be interesting to see what comes out!
-Tim
 
   / Hydraulic Oil Replacement #6  
I need to change my hydraulic fluid in my Kubota shuttle and intend to use Deere Hy-Gard. It takes 11 gallons. Does anyone know if the auto stores that recycle engine oil take hydraulic fluid?
 
   / Hydraulic Oil Replacement #7  
I haven't had an issue in my area (ON, Canada). It usually looks like fairly clean oil, so the likely issue might be quantity - not too many consumer level oil pans hold 11 gallons.

So... check b4 you haul all 11 gallons, and you might want to post your location Joe - somebody in your area may have recommendations.

Always can try an ag dealer, or any full service garage. Around here, shops either don't pay to have it hauled away, or get a small credit - YMMV, depending where you are.

Rgds, D.
 
   / Hydraulic Oil Replacement #8  
Hydraulic oil is essentially the same as motor oil, with a different set of chemical additives.

Don't feel guilty for slipping it in oil recycling, the reprocessing plant can't tell the difference.
 
   / Hydraulic Oil Replacement #9  
What is Power Trac's recommendation? I do recommend the 15w 50 Mobil 1 synthetic. I have been using it for about 11 years. The torque increased considerably from the 5w30 that was originally in it. Is it time to change it? Only about 5 gallons will come out. Is that enough. I wonder it I could just drain the bottom gallon or so in the reservoir after letting it sit for a few days.
 
   / Hydraulic Oil Replacement #10  
 
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