The Komatsu Excavator hydraulic system runs using oil as the main fluid for lubrication for all its components. Oils that are generally used within this system are proprietary to the Komatsu brand. This is because Komatsu has designed these fluids to offer smooth and quiet running of the excavator’s various hydraulic components in addition to offering optimum protection for the system at all times.

The oil used for the hydraulic system is usually categorised into one of these four groups which include RG, RH, RK, and WK series oils.

No, you cannot use motor oil in your Komatsu Excavator hydraulic system.

There are many differences between motor oil and hydraulic fluid, but one of the most important is that motor oil can only be used to lubricate the internal parts of an engine and hydraulic fluid can be used as both a lubricant and a hydraulic medium.

All hydraulic systems require some type of hydraulic fluid to operate. The three main types of hydraulic fluids are petroleum based oils, water based fluids, and synthetic or semi-synthetic fluids. Each type has its advantages and disadvantages, but regardless of type all hydraulic fluids perform the same basic functions. The primary function of any hydraulic fluid is to provide a pushing force to move the components in a hydraulic system.

Hydraulic fluids are incompressible and therefore when pressurized can transmit forces throughout the entire length of a pressurized system without significant loss of energy or efficiency. Unlike air, which is compressible, even a small leak in an air system will cause the pressure within the system to drop rapidly and significantly reducing the force available at any given point within the system.

Komatsu Excavator hydraulic system

Komatsu Excavators need special lubricating oils that conform to certain specifications.

These oils are subjected to high temperatures and pressures within the machinery, and the hydraulic system is critical for smooth operation. Some constructors and plant owners try to save money by using motor oil in their hydraulic systems, which can create problems. High Temperature Operation Komatsu excavators are designed to withstand heavy use and tough conditions. Hydraulic oil is subjected to intense heat as it circulates through the system, so a high flashpoint (the temperature at which oil begins to turn into a gas) is essential.

Motor oil doesn’t have the same kind of heat resistance that specialized hydraulic oil does, which can increase wear and reduce efficiency. Filter Clogging Hydraulic systems operate at high pressures, and small particles in the oil can cause damage as they circulate through the system.

The pumps in Komatsu excavators require filters that are much smaller than those used in a car or other vehicle, so motor oil with larger contaminants can clog them more quickly. This can lead to premature pump failure and increased maintenance costs.

Effect on Seals High-quality motor oils contain additives that can be damaging to seals, causing them wear out faster than expected or even leak fluil.

Motor oil is not formulated for the high pressures and temperatures that Komatsu excavators experience.

Komatsu excavator hydraulic oil should be rated to at least Komatsu standard KES 07.890.1, and under certain conditions up to KES 07.890.5. This is not just the same as ISO VG 46 or ISO VG 68 hydraulic oils, those are only a starting point for minimum viscosity requirements.

Many other equipment manufacturers have their own standards for hydraulic oil that are more strict than the ISO standards, and Komatsu is among them. Komatsu’s specifications address the high temperatures and pressures that hydraulic systems can experience during boom swing and boom/arm float operations, which can exceed 1000 psi (69 bar) at the pump outlet.

Motor oils are not designed for these conditions, so using motor oil in an excavator would probably result in accelerated wear of the pumps and motors as well as higher fuel consumption due to increased friction in the system.

Using motor oil could actually damage Komatsu excavator.

The Komatsu Excavator hydraulic system consists of several components that work together to move the boom, stick, bucket, and other attachments. The hydraulic pump and motor, hydraulic cylinder, directional control valves, coolers and filters, accumulators, and various sensors make up the basic components of a hydraulic system.

Komatsu Excavator is also a complex mechanical device that requires high-quality oil. It is important to use the right kind of lubricant to avoid damaging or breaking your machine. The Komatsu Excavator’s hydraulic system uses a special type of oil called “hydraulic fluid.” Hydraulic fluid is a non-compressible liquid that is used to transmit force applied at one point to another point using an incompressible fluid.

In other words, it acts like an invisible pipe connecting two points. Hydraulic systems are used in many machines such as forklifts, excavators and bulldozers to provide power for moving heavy objects. The hydraulics work by pushing oil through a series of small pipes which creates pressure on the piston inside each pipe. This pressure moves the piston back and forth creating movement in one direction or another depending on which way it is pushed.

You should avoid using motor oil in your Komatsu excavator’s hydraulic system.

Hydraulic fluid is the lifeblood of heavy equipment. It transfers power from the engine to the hydraulic components, which control movement, steering and a variety of other functions.

As with any lubricant, though, there are certain types of hydraulic fluids that are best suited for particular circumstances. If you use the wrong type of fluid in your Komatsu excavator’s hydraulic system, you may experience a range of problems including reduced efficiency and shortened service life. Although it’s possible to use motor oil in your excavator’s hydraulic system, it’s not recommended. Motor oil is designed for automotive engines.

Although it may temporarily work just fine in your excavator, it will break down much faster than hydraulic fluid that’s specifically designed for this application. Motor oil will also gum up the system more quickly than hydraulic fluid and cause deposits to build up on valves and seals, which can lead to reduced performance or even catastrophic equipment failure.

If you want to ensure optimal performance from your Komatsu excavator, be sure to use only high-quality Komatsu genuine parts and fluids. Komatsu Genuine Parts deliver factory-level performance at competitive prices and are backed by standard factory warranties against defects and failures due to wear or damage under normal operating conditions.


This message is for Mr. Tony Curtis. You might know him and his company as CUSTOM FILTERS OF AMERICA, INC. I had contacted them when I was having problems with hydraulic pump in my KOMATSU WA300-3N, I have broken my hydraulic pump and thought that I could purchase a used one in Australia. When they received the model of my machine they started to tell me that pressure from the pump is so high it’s not recommended to use oils with higher VISCOSITY than 10W40 (or 10W30) .

When in doubt about viscosity you must consult the operator manual or warranty information regarding your excavator. I follow what he told me and change the oil filter, oil, hydraulic pump and housing gaskets. Now the pressure is more low than before but still not ok. Being that the pumps cannot handle this type of thicker oil ?? any help please…

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