What's the best oil for Hydro Pumps for zero turn

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55
Location
Virginia, USA
Hi; I'm very hopeful that there is enough talent here to really figure this out. I'm talking about the hydro pumps used to pump the oil through the hydro wheel motors on commercial zero turn lawn mowers. Lets start with a very common oil recommended in some very popular commercial brands:(Mobil 1 15W-50) Now this oil has 1200ppm Phos. & 1300ppm Zinc and when I asked Mobil if it had friction modifiers, they said yes. So what is it in an oil that would be best suited for the hydro pump to keep it from failing? To my understanding the pump is more prone to failure than the wheel motors. Should we try and use a true synthetic oil (PAO) Base? Try for more Zinc? Try for more Phosphorus? Try oil with a high ppm of Moly-?? Please share what you may know. Many-Thanks
 

j454

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55
Location
Virginia, USA
OK, Don't make too much fund of me...I'm still kind of new here and have near zero history as a lurker. So what is "THF"??
 

JTK

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13,164
Location
Buffalo, NY
I'd use Shell Rotella-T 15w-40. Long hydrostat life if more about not overheating the units, than the brand of oil used. If the unit does inherently run hot in your application, a synthetic blend or full synthetic would be beneficial. There's more movement and pressure swings in the hydros, making them more vulnerable to failure than the hydraulic wheel motors. Joel
 
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7,742
Location
MI
THF stands for Tractor Hydraulic Fluid, sometimes also called UTHF for Universal Tractor Hydraulic Fluid. It is a common fluid used in agriculture tractors that share a common sump for transmission, hydraulic, and wet brakes. IMO, a lot different than a zero turn wheel motor/pump application. I use what the manufacturer recommends. Exmark just came out with their own hydro oil. There is a good debate over at lawnsite.com regarding it's merits vs. their previous Mobil 1 15W50 recommendation. http://www.lawnsite.com/showthread.php?t=265441 http://www.exmark.com/Exmark_Oil.htm
 

j454

Thread starter
Messages
55
Location
Virginia, USA
Thanks for THF definition and the links. As best I can tell so far, it looks to be two types of hydro systems on these machines. One type has a large reservoir with a larger quantity of fluid to aid in cooling and usually specs. dino oil. The other has a very small reservoir and it usually specs. a synthetic oil because they already know it will be hot. It's the system with the small reservoir I'd like to focus on.
 

JTK

Messages
13,164
Location
Buffalo, NY
Any commercial unit I've seen specs 15w40 or 20w50 across the board; Hydro-Gear hydros and Parker wheel motors would be your most common combo. I've never seen one spec THF. Joel
 

j454

Thread starter
Messages
55
Location
Virginia, USA
 Originally Posted By: JTK
Any commercial unit I've seen specs 15w40 or 20w50 across the board; Hydro-Gear hydros and Parker wheel motors would be your most common combo. I've never seen one spec THF. Joel
A lot of them also spec. 15W-50 MOBIL 1
 

j454

Thread starter
Messages
55
Location
Virginia, USA
 Originally Posted By: doitmyself
THF stands for Tractor Hydraulic Fluid, sometimes also called UTHF for Universal Tractor Hydraulic Fluid. It is a common fluid used in agriculture tractors that share a common sump for transmission, hydraulic, and wet brakes. IMO, a lot different than a zero turn wheel motor/pump application. I use what the manufacturer recommends. Exmark just came out with their own hydro oil. There is a good debate over at lawnsite.com regarding it's merits vs. their previous Mobil 1 15W50 recommendation. http://www.lawnsite.com/showthread.php?t=265441 http://www.exmark.com/Exmark_Oil.htm
It looks like this ExMark hydro oil is also a 15W-50, and a group III oil. ExMark claims you can run it for twice the initial amount of hours compared to Mobil 1 15W-50, ExMark oil @ 500 Hours, Mobil 1 @ 250 Hours. From what I've read there at the lawnsite forum, the ExMark oil has 1071ppm Zinc @ 1631ppm Phosphorus. While the Mobil 1 15W-50 has 1300ppm Zinc & 1200ppm Phosphorus. What is it that makes the ExMark oil good for twice as long run time? Could it be all that Phosphorus??
 
Messages
7,742
Location
MI
 Originally Posted By: j454
What is it that makes the ExMark oil good for twice as long run time? Could it be all that Phosphorus??
I was taught that you cannot judge the quality of a book...er, oil by it's cover, or comparing it's specs only. Two oils could have the exact same specs., yet one could be better due to better quality base stock and additives. The late Stinky Peterson of Butler/CAT Oil Labs taught me this. He said that a HDEO (Diesel Oil) with a TBN of 10 could out perform an oil with a TBN of 12 for this very reason. It would be interesting to see if Exmark's claim is more than marketing hype. I think their claim only holds for the new '09 mowers and up. Maybe they added an oil cooler??
 

JTK

Messages
13,164
Location
Buffalo, NY
 Originally Posted By: doitmyself
..It would be interesting to see if Exmark's claim is more than marketing hype.
No doubt it is. Most of your OPE manufacturers try to push their own branded oils at ridiculous cost. A prime example is Cub Cadet's "Drive System Fluid Plus" at ~$9/qt. It's made by Shell and is an every day synthetic blend HDEO that can be had off the shelf for a fraction of the cost. 'Nother thing for the OP to keep in mind; 1) Exmark doesn't make hydros or wheel motors, so you can go by what the manufacturer suggests as well. 2) Lastly, there's no appreciable difference between 15w50 and 20w50 that should make you sweat the difference. Joel
 
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5,069
Location
Saratoga, NY
Um <b>j454</b>, for these less-than-obvious applications, I like to start with the factory spec and go from there. What does the manual say in this case?
 
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931
Location
Michigan
After reading all this and some research...it's possible that M-1 MX4T 10W-40 is a great choice. It's a robust motorcycle oil with 1600 ppm of zinc and phos like it's big brother M-1 V- Twin 20W-50 also with 1600 ppm zinc and phos. Either might be a best choice in a 50 wt. I like 5W-30 Amsoil hydrostatic oil for my Hydrogear. Very smooth operation.
 
Messages
931
Location
Michigan
One additional comment.... Theses days with low zddp for automobil oils a good way to pretty much always have made a good selection in a robust oil is to choose a motorcycle oil Check out the vou's here on M-1/Amsoil/Motul/Redline/RP....always rubust! Can't go wrong with motorcycle synthetic oil or diesel SL rated oil...Rotella etc...it's a no brainer.
 
Messages
601
Location
sweden
Arent we talking about a hydraulic drive system? Why use engine oil?- do yuo have soot, cumbustion blowby etc in your drive. I dont think so, so why use oil for whats not in there? Still say THF.( or if you really want soot control STOU)
 
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7,742
Location
MI
 Originally Posted By: ac_tc
Arent we talking about a hydraulic drive system? Why use engine oil?- do yuo have soot, cumbustion blowby etc in your drive. I dont think so, so why use oil for whats not in there? Still say THF.( or if you really want soot control STOU)
That's a good question that I hope one of the experts here will answer....Molekule??? My workplace has this very robust chipper that specs. 10W30 engine oil for it's hydraulic system: [image] http://www.banditchippers.com/image.php?...g)+x(430)+q(80) [/image]
 
Messages
87
Location
New Jersey
I've got a Scag and the manual calls for 20w 50 engine oil. I put in Maxlife 20w 50 thinking that the seal conditioners may help keep everything nice and tight.
 
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