Change out factory hydraulic fluid to synthetic

mobilcastle

Well-known member
With the slides in I would think that most of the fluid is in the reservoir- how hard is it to drain and refill with synthetic? Do you have to pump it out of the tank to change it? Cold weather is hard on the motor pushing the cold fluid. Anyone changed theirs out? If yes what did you replace it with? Did you notice a big difference?
Thanks,
Steve
 

caissiel

Senior Member
The cylinders stay full in both sides of the piston. These cylinders are pressure 2 way unlike a Jack that will completely empty on side when post is in. Caveties are all filled with oil. That's why a small reservoir is used. Transmission oil used is good for very cold conditions and is also mostly synthetic anyway. Its a chance to introduce more dirt in the system.

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TedS

Well-known member
ATF is intended to be easy to pump at low temperatures, that's why it is used in automatic transmissions. No need to change it.
 

danemayer

Well-known member
It does get sluggish when temps are below zero (F). I broke camp at about -5 (F) a week ago. The auto-leveler jacks popped the breaker 4 or 5 times and the DS slideout popped the breaker twice. Might be that the breaker is a little weak, but it works fine at normal temps.
 

mattpopp

Trouble Maker
I never got around to look at how the hydraulics are plumbed back to the pump/tank on these units. But the pump will supply a manifold. From the manifold will divert the require pressure/flow (which is preset by the pump)through solenoids. During any function you will have a return of flow back to that manifold and from that manifold back to the tank. That return line is common to all functions between the manifold and pump.

Now the above statement is assuming the Manifold and pump are separate units. If that are built as one unit then my below statement is kind of worthless but maybe not. There could be a designated port on the unit to do what I mention below.

So if I was going to replace the fluid in the system. I would remove the return line at the tank and run it to a bucket. Drain the tank and fill it with the new fluid. Then function every hydraulic part on the RV to full extend and then fully retracted three or four times. You must go full travel both directions as that will ensure you are pushing out all fluid on the back side of the piston in the cylinders. Though from the factory the slide out cylinders may be limited on full travel, if so then all you can do is what you are limited to. But you have to monitor the volume in the tank as you will not be returning any fluid to the tank. As it will all be going into the bucket.

If the entire system held 4 gallons(which I have no idea of what the volume is), that's including the volume in all of the lines, cylinders, tank, and manifold. Mi would not be satisfied until I had a bucket or two totaling twice that.

Doing it this way will also ensure that you do not introduce any air into the system assuming you monitor the volume in the tank. You also reduce the likely hood of getting any contaminates in there also. Getting air in the system would or could be a nightmare.

The function of a hydraulic cylinder has two sides, Piston end and Rod End. Side of the piston that is attached to the Rod is called the rod end. Kind of self explaining. Fully retracted there is less oil volume in the cylinder then when it's fully extended. That's due to the rod consuming part of the internal volume of the cylinder when retracted. Also, every cylinder exerts a greater force extending then when retracting. Again that is due to the rod consuming surface area of the piston on where they attach. Loss of surface area means less surface area for the hydraulic pressure to react against. So if you ever have a slide that will push out but sticks on the way in that could be a partial reason. The cylinder doesn't have as much power retracting.

I have over 12yrs with practical experience with hydraulic. One thing that I have learned about oil in all regards is each brand whether dyno or man made can have dramatic effect of the efficiency of the system. Obviously the cold the climates will cause the pump to consume more energy as the oil becomes thicker. Where I live the current ATF that is in my toy hauler hydraulic system is just fine. But if I was going to switch for colder climate it would be Royal Purple without thought. Some years ago we switched all of our deck equipment on the vessel to Royal Purple Hydraulic Oil. Instantly in every piece of equipment we noticed two things. They where quieter and there operating temps dropped. Over time we also found that we had less failures from the hydraulics (this was noticeable as all repairs are logged and it was easy to see the trend over a years time). I am a firm believer in the Purple oil.

By the way, which ATF do these systems use? If its the ATF-4 I believe it only comes as Group III. Meaning its synthetic no matter what brand you buy.

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lwmcguir

Well-known member
With the slides in I would think that most of the fluid is in the reservoir- how hard is it to drain and refill with synthetic? Do you have to pump it out of the tank to change it? Cold weather is hard on the motor pushing the cold fluid. Anyone changed theirs out? If yes what did you replace it with? Did you notice a big difference?
Thanks,
Steve
There is hardly any difference in the reservoir volume with the slides in or out, nor should there be. What would the advantage of changing the fluid be in a system that cycles very little. In a truck, car, tractor and so on the hydraulic fluid is working all the time and you can use it for years.
 

TedS

Well-known member
From the Lippert manual: The [FONT=Arial,Italic][FONT=Arial,Italic]Lippert Hydraulic Slideout and HLG System [/FONT][/FONT]uses automatic transmission

fluid (ATF). Any ATF can be used. A full synthetic or synthetic blend works best

such as Dexron II, Dexron III or Mercon 5. For best operation, fill system within

1” of the top when all slideouts and landing gear are completely retracted. The

see through reservoir makes it easy to check oil level. It is recommended that

the oil level be checked prior to operating the system. Make sure the breather

cap is free of contamination before removing, replacing or installing. In colder

temperatures (less than 10° F) the cylinders and jacks may extend and retract

slowly due to the fluid’s molecular nature. For cold weather operation, fluid

specially formulated for low temperatures may be desirable.
 

mattpopp

Trouble Maker
There is hardly any difference in the reservoir volume with the slides in or out, nor should there be. What would the advantage of changing the fluid be in a system that cycles very little. In a truck, car, tractor and so on the hydraulic fluid is working all the time and you can use it for years.

It cycles a lot more then you think. How ever much volume is needed to push the piston in the cylinders from retracted to extended during a sliding out the slide is the amount of fluid being cycled. Vice versa during sliding the slide in.

The difference in volume you see from a slide in either position is only determined by the amount of volume the rod in the cylinder displaces inside of the cylinder. Small rod little difference in the tank, large rod then you see a large difference in the tank.

For most people, they would only change the fluid if they are camping/traveling in very cold climates. Put a better suited fluid in there for the cold. Otherwise that fluid should be changed after a set time or a set estimated operated hours. ATF or hydraulic oil breaks down like any other fluid from being heated and pressurized. I would think after at least 5 years you would want to change the fluid.


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TedS

Well-known member
The fluid will not get nearly hot enough to ruin the additives. You will probably never have to change it.
 

mattpopp

Trouble Maker
The fluid will not get nearly hot enough to ruin the additives. You will probably never have to change it.

It does build up heat for a moment in the pump (as that is the nature of attempting to compress fluids) and more then likely some through the manifold. Though you are correct as it will never generate enough heat to heat up the entire system.

Has anybody ever put there hand on the pump or manifold after setting up the front jacks, 6pt level, or running the slides. I haven't but I am curious if you can feel any heat generation.

Over time you will build up contaminates in the system from use. As the pump, seals, orings, and any other moving parts wear. It all leaves trace amounts that generate to substantial amounts in time.


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lwmcguir

Well-known member
It cycles a lot more then you think. How ever much volume is needed to push the piston in the cylinders from retracted to extended during a sliding out the slide is the amount of fluid being cycled. Vice versa during sliding the slide in.

The difference in volume you see from a slide in either position is only determined by the amount of volume the rod in the cylinder displaces inside of the cylinder. Small rod little difference in the tank, large rod then you see a large difference in the tank.

For most people, they would only change the fluid if they are camping/traveling in very cold climates. Put a better suited fluid in there for the cold. Otherwise that fluid should be changed after a set time or a set estimated operated hours. ATF or hydraulic oil breaks down like any other fluid from being heated and pressurized. I would think after at least 5 years you would want to change the fluid.


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I was referring to how many times you will actually operate the hydraulic system which I would suspect if a few times a week at maximum and for only a few months for most folks. A tractor or skid steer recycles the fluid constantly for hours, days, and weeks and of course that is why they have filters. There would never be any need to change out the hydraulic fluid in a camper. The hydraulic fluid will outlast everything else that it is made up of. That was where I was coming from. We have had hydraulic units since they started making them for campers and never had an issue nor expected to have them. It really isn't anything to be concerned about. Either you have a good system or you don't. Nothing wrong with changing it out if you want to have something to do and spend money on.
 

caissiel

Senior Member
Last unit was 15 years old with all original ATF fluids. And I live in North and opererated the slides in cold climate. I would be more concerned with the harder rubbers of the slide seals.

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lwmcguir

Well-known member
Last unit was 15 years old with all original ATF fluids. And I live in North and opererated the slides in cold climate. I would be more concerned with the harder rubbers of the slide seals.

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Well Stated. If you want to worry make it worthwhile.
 
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