A Complete Guide to Hydraulic Jack Oil

Hydraulic oil is a low viscosity, non-compressible fluid which is responsible for moving the piston, thus, power in hydraulic machinery. Hydraulic fluid can be mineral-based or synthetic.

Changing hydraulic jack oil can be traumatic for beginners. Is it your first time to change jack oil and you have no idea where to begin? Then you are in the right place. This is the definitive guide that will direct you step by step on how to go about the entire process. Not only will it educate you on why it is important, but also when you should do it.

Why you Consider Hydraulic Jack fluid

A hydraulic jack is an important instrument whose main use is to lift heavy items, especially vehicles. The mechanism of operation involves a piston and fluid. The fluid helps move the piston upon loading and offloading. The point is, without the fluid, the hydraulic jack is rendered useless. The fluid is part and parcel of the jack.

Continuous usage of the hydraulic jack reduces the oil level, and this has an adverse effect on the performance of the jack. This necessitates changing the oil to improve the performance of the jack. The more you use the jack, the higher the frequency for changing the oil.

So, how will you know its time to change the oil? First, check the level of the fluid regularly. Change the oil when the level falls below the normal range. The other factor that can tell you its time to change the fluid is the performance of the jack. When it starts resisting to lift objects or stops working efficiently, check the fluid level and replace it.

Types of oil You Can Use as Jack Oil

When it is evident you need to replace jack oil, the next issue is to identify the type of fluid that is suitable for your hydraulic jack oil. There are some guidelines you should have in mind as you go shopping for the fluid.

Features of suitable hydraulic jack oil

  • Oxidative
  • Thermal stability(works within a high range of temperatures
  • Non-corrosive
  • Filterable and clean
  • Anti-wear
  • Hydrolytic stability
  • Fire resistant

Hydraulic jack oil viscosity

This is one of the most important aspects of the fluid to be used in a hydraulic system. The viscosity of a hydraulic fluid is measured in Centistokes(cSt) at either 1000C(SAE) or 400C(ISO).

Hydraulic oil additives

These are added to the hydraulic fluid to ensure longevity. Some of the additives allow the jack to perform better in diverse conditions. Here are some of the most popular additives.

  • Anti-rust. It reduces rust damage from oxidation by forming a protective layer
  • Anti-wear. It increases the durability of the hydraulic machinery and components
  • Anti-oxidant. It allows the equipment to operate for long without necessitating oil change
  • Cold flow. It enables the jack to operate in extremely cold areas

Fluids you should not use

Can I use motor oil in my floor jack? You SHOULD NOT even think about it. You might think that brake oil or motor oil can be used as an alternative to hydraulic jack oil. These oils lack the viscosity required in a hydraulic jack fluid. Brake oil has alcohol, which can break the seals in the system. The functions of a hydraulic jack fluid revolve around power transfer and control. Therefore, it has to be non-compressible, fast air release, low volatility and should have low foaming properties.

ATF(Automatic Transmission Fluid) can be used as an alternative to hydraulic oil depending on the viscosity of the fluid. However, some issues come up when using ATF as a hydraulic fluid. For instance, the additives in ATF can break down the hydraulic seals. Unlike hydraulic fluids which are designed not to foam in high pressures, Automatic Transmission Fluid is prone to foam when subjected to very high pressure. Finally, some cylinders are designed to work with particular fluids. And when that fluid is not used, the full potential of the cylinder is not unleashed. If it is a small hand-operated hydraulic jack, you can use ATF. Otherwise, refrain from using it.

Therefore, to ensure maximum efficiency of the jack, use the proper fluid specifically produced for a hydraulic jack. The warranty for a specific jack specifies the fluid to be used. If you use a different fluid, the warranty becomes null and void.

Oils recommended for hydraulic jacks

Some of the best products in the market are:

  • ISO 150
  • AW32 Hydraulic jack oil

You may be wondering why these two products are recommended? Well, they are certified by ISO and they have a high ranking. The viscosity of these products is 10W which is the recommended viscosity for hydraulic jack oil. They operate at a temperature range of -300C and 1400C, meaning they can perform effectively in any circumstances. In addition, the two products are created under extreme pressure and contain additives that make them perfect for use in hydraulic jacks.

Tools required when changing hydraulic oil

After selecting the suitable oil for your jack, the next step is to assemble the tools required for changing the fluid. Relax, you don’t need a huge list of complicated equipment to change the oil. As a matter of fact, you have most of the tools in your toolbox. You need the following tools for the process:

  • Oil gun dispenser
  • Screwdriver
  • Drain bucket

Here is the detailed guide about Changing Hydraulic Jack Oil .

What if you did not change jack oil?

It is essential to understand the disadvantages of not changing hydraulic oil when the need arises. Condensation will occur, which will make the piston pump plunger to rust. Eventually, the plunger will break the seal. Therefore, change the oil as soon as you realize it is below the level or has been contaminated,

Alternate of hydraulic jack oil

Machine oil or lightweight motor oil of 10/20W can be substituted for hydraulic fluid. Automatic transmission fluid can function as hydraulic fluid. Use it if you are stuck and do not have the oil recommended by the manufacturer.

There are a few vegetable seed oils that can be commercially used as hydraulic fluids. They include oils extracted from sunflower, soy, and Canola seeds. The performance of these oils varies with the type of additives and base oil chosen. The vegetable seed oil has several advantages over their mineral counterparts when used as hydraulic fluid. The advantages include higher flashpoints of 3200C, they are non-toxic, higher lubricity, and biodegradable. Some of the limitations of vegetable oils include low oxidation resistance and poor performance in low temperature. In addition, vegetable oil is quite expensive.

You should be very careful when searching for substitutes for hydraulic fluid. If you use the wrong fluid, the seals can swell or break. Therefore, do not substitute unless you are very sure of what you are doing.

What are grade in hydraulic jack oil and recommended value?

Fluids for hydraulic jack are measured differently. Hydraulic jack oil grade refers to the ISO viscosity. They are measured using the ISO scale, and not the SAE scale. ISO grades hydraulic fluid by measuring the viscosity at 400C(1040F). For instance, ISO 32 fluid will flow quickly than ISO 68. You can think of the numbers as, the lower the value, the thinner the fluid.

Temperature affects the viscosity of the oil. As temperature rises, the oil becomes thinner. The opposite is also true.

Anti-wear Hydraulic Jack Oil Grade

Most hydraulic fluids are measured with the typical ISO grade. However, there are some hydraulic fluids with anti-wear properties. These are measured with different grading. You could have come across an AW 46 oil. What does this mean? An AW oil will perform the same as their ISO counterparts. The main difference is that anti-wear hydraulic fluids contain other additives for reducing corrosion. Anti-wear oils ensure there is no metal-to-metal contact within the system.

Zinc is the commonly used additive in anti-wear oils as it extends the durability of the machinery. The other reason for using zinc-based additives is because they have both anti-wear as well as anti-oxidative properties. Anti-wear hydraulic oils are recommended when operating in a harsh environment.

If you use a fluid that is too thick, the machine may not be able to draw the oil effectively from its reservoir. This may lead to cavitation. On the other hand, using thinner oil may lead to internal slippage within the jack, thus, reducing its efficiency.

A hydraulic jack operating in a cold area will perform better with a low hydraulic jack oil grade of 32. Why? The oil will be thin, thus, pose less resistance to flow. If the hydraulic system manufacturer specified the grade of oil to use, it is advisable to use it. The manufacturer tested the system to determine which grade is best for the jack.


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