Hydraulic Fluid For RV Jacks (What Type of Hydraulic Fluid)

This is a no-brainer. Hydraulic fluid for RV jacks is not that varied. That means that you can use just about any hydraulic fluid brand as long as it is compatible with the brand you have in your hydraulic system currently. Some systems prefer using their own brand of fluid so read your owner’s manual carefully.

Most hydraulic systems for RV jacks will use Dexron III. It is the one that is the most accessible at this time. There are some clear brands you can use but those clear-colored fluids make it very difficult to spot a leak. The Dexron III red makes it very easy to spot one.

To learn more about which hydraulic fluid to use in your RV jack system, just continue to read our article. It explores the topic so you have the best information possible when you need to refill or replace your current hydraulic fluid.

What Type Of Hydraulic Fluid For The RV Leveling System


As reported earlier, the best hydraulic fluid to use would be Dexron III. It is specially formulated for modern hydraulic systems including RV jacks. This fluid is specially formulated and has high temperature tolerances, and top protection properties against oxidation, as well as wear and tear.

If you do a lot of camping in extreme temperature locations, then you may want to consider going to a synthetic option. These synthetic brands are well suited for extreme camping situations but they do come at a higher cost.

If you want to have the best of both fluids, there are some semi-synthetics that combine the synthetic with mineral-based fluids so that you have the ultimate protection for your leveling system.

Then, you may find that different leveling jack manufacturers make their own or have their own brand made for their systems. They prefer that you use their hydraulic fluid for the utmost performance.

The owner’s manual should give you information on which fluid you should use and which one you can use.

Can I Use Transmission Fluid For The Hydraulic Jack?

Yes, you can. This is what Dexron III is. It is automatic transmission fluid or ATF and it is perfect for your leveling jack system. Dexron III is one of the most commonly recommended fluids for any RV hydraulic system

This product is cheaper than synthetic or manufacturer brands and can be found in more locations. The only thing you have to do is make sure it is compatible with the manufacturer’s brand in your current system.

Some manuals for non-Dexron III using leveling jacks will state not to mix hydraulic fluids so watch out for that warning. Then watch out for those hydraulic fluids that are compatible with Desron III.

These different brands, like AW32, can be used in leveling jack systems but do not have the ingredients to work in your transmission. Compatibility is not always a two-way street.

You should be able to use Mercon 5 in some Lippert systems as well as other brands of leveling jacks. Check the owner’s manual to see what the manufacturer recommends and stick with that brand.

Best Hydraulic Fluid For RV Leveling Jacks


There are some good brands on the market. We have mentioned Dexron III and Mercon 5 both of which will not damage your leveling jack systems. But there are other brands to consider. HWH would be one of those but the best ones are made for specific temperatures.

For example, for temperatures above 32 degrees F, you will want to use:

- Dexron® III/Mercon® ATF

- Mercon® V ATF

- Dexron® VI ATF

- PetroBlend (Mason City, IA) PHO 0022S (synthetic group 3 base blend)

- Bellman all temp 22 (Bremen, IN)

- Or any ATF or hydraulic fluid with a pour point lower than -42 °C (-44 °F).

For temperatures below 32 degrees F, you can choose to use:

- Mobil 1™ full synthetic ATF

- Royal Purple® full synthetic ATF

- Valvoline™ full synthetic ATF

- Amsoil® full synthetic ATF

- PetroBlend (Mason City, IA) PHO 0022S (synthetic group 3 base blend)

- Bellman all temp 22 (Bremen, IN)

- Or any ATF or hydraulic fluid with a pour point lower than -45 °C (-45 °F).

- Multivis (all temperature) ISO 22 hydraulic fluid

- Or any ATF or hydraulic fluid (conventional or synthetic) with a pour point lower than -46 °C (-50 °F).

And for temperatures lower than 0 degrees F here are your options:

- Kendall® Hyken Glacial Blu

- Benz oil (Milwaukee, WI) Flomite 530

- Or any conventional or synthetic ATF or hydraulic fluid with a pour point less than -57 °C (-70 °F) and viscosity less than 2850 cP (3282 cSt) @ -40 °C (-40 °F ) (source)

HWH Hydraulic Fluid

This is one brand of fluid that is made especially for HWH leveling and hydraulic jack systems. Its ingredients are carefully formulated to work with finely-tuned HWH systems to bring maximum performance all the time.

It should work down to - 20 degrees F and it is getting top reviews from users. On the Amazon review page, it is getting 100% 4 or 5-star ratings. Users are very happy with the performance they receive and like the fact that it is colorless.

Many people are worried about the Dexron III red color as it leaves some bad stains behind if there is a leak. Not so with HWH fluid. The cost is just about $22 for one quart but so far no one is warning anyone away from using it.

What makes it a top product is that it seems to be specially formulated for RV and trailer use, all varieties of RVs and trailers.

How Much Fluid Does an HWH Leveling System Hold?


We checked the HWH corporation's official fluid change instruction sheet and we checked other resources as well. The only thing these documents stated for the actual amount was- to fill the tank till it is one inch below the top of the fill hole.

That is it. Here is a link to the official instructions to purge the old fluid and add new. The instructions are quite long and may seem a little complicated but after doing it one or two times, it should come a lot easier.

The manual for the joystick HWH leveling jack system also does not provide any actual fluid amount that needs to go into the system. It says the same thing, stay an inch below the top of the fill opening.

The manual also says for their system:

FLUID: HWH Specialty Hydraulic Oil is recommended. In an

emergency Dexron automatic transmission fluid can be used.


Dexron automatic transmission fluid contains a red dye

and can cause staining should a leak occur. DO NOT USE

brake fluid or hydraulic jack fluid. Use of these can damage

Seals” (Source)

What Kind Of Hydraulic Fluid For RV Slides?

To be on the safe side, you should use the recommended fluid that is listed in your manual. As you can see by the example above, HWH has its own brand that prefer you to use.

There will be other companies with the same attitude. However, you can use Dexron III as it is compatible with most hydraulic leveling jack systems. Just read your manuals carefully so you do not miss any warnings.

As you can see, it will be the seals that will get damaged if you use the wrong fluid, and that will create a nice repair bill for you. Follow the recommendations in your owner’s manual as the company that built the system knows it the best. They know which is the best fluid to use.

Hydraulic Fluid For RV Slide Out


For the Lippert slide-out systems, you can use any automatic transmission fluid on the market today. One of their manuals states that Dexron III or Mercon 5 are the best synthetic options to use.

That is what you will have to do when you buy your new RV or trailer. You will have to check the manual to find the specific fluid you need to use for the slide-out brand in your RV, etc. Then follow that recommendation.

This is not rocket science and it is a very simple system to work with if you know what you are doing. Just do not use any incompatible fluid that happens to be the cheapest.

Some Additional Words

When it comes to hydraulic systems on your RV, everything is very simple and straight forward. The key is to make sure you always use the right fluid for the brand system you have in your RV or trailer.

This applies to leveling jacks, slide-outs, or any other hydraulic system you have. The key is not to use any stop leak products if you find a leak and do not mix fluids.

Keep everything pure so that your system will not get fouled up and stop working on you. You do have a lot of fluid leeway in some systems.

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