Hydraulic Oil ISO AW 32, 46, 68, 100: How to Choose the Right Grade for Your Machine
Once a hydraulic system begins to fail, most owners think the machine is the problem. Slowness of work, strange noises, or overheating of pumps, valves, and cylinders are frequently attributed to these causes. The issue, however, most of the time starts with a much easier-to-fix problem: the incorrect grade of hydraulic oil viscosity.
The blood of any hydraulic system is hydraulic oil. It transfers power, lubricates moving components, dissipates heat, and coats components to protect against wear and corrosion. An incorrect ISO AW grade may reduce efficiency, increase energy consumption, accelerate wear, and even shorten the machine's life.
Typical grades of hydraulic oil include ISO AW 32, 46, 68, and 100, which vary in viscosity and flow characteristics and are selected based on machine type, load, temperature, and working conditions. The grade of choice is important for performance, reliability, and durability.
Understanding ISO AW and Viscosity
The ISO AW (International Standards Organization Viscosity Grade) is a standard that classifies hydraulic oil by the kinematic viscosity at 40°C. The lower the number, the thinner the oil; the higher the number, the thicker the oil.
The viscosity is important in that the hydraulic oil has to flow efficiently through the pumps, hoses and the valves and still has to provide a protective lubricating film on the moving metal surfaces. Excessively thin oil may cause wear of the pump and low pressure, whereas excessively thick oil may cause decreased responsiveness to the system, and higher energy usage.
ISO AW 32: Fast Flow, Light Load
The thinnest of the common grades is ISO AW 32. It has a low viscosity, which enables the flow to be rapid and quick response and therefore, it is suitable in high-speed low-load systems.
Typical use is CNC machines, small presses, injection molding machines, and precision hydraulic systems. The lightweight oil is to minimize the loss of energy and circulation particularly in cold starting.
However, ISO AW 32 might fail to protect high load or high temperature pumps and valves. Its application in a place where it is not advised to be used, such as where it is recommended to use thicker oil, may cause increased wear and early failure of the system. If you are looking for a premium quality ISO AW 32 hydraulic oil you can try our Atlantic X Hydraulic Oil AW 32.
ISO AW 46: The Industrial Standard
The ISO AW 46 is a balance between the load and flow protection. It is the most widespread industrial hydraulic oil, and can be used in moderate-speed, moderate-load applications.
You’ll often find ISO AW 46 in industrial presses, forklifts, machine tools, packaging equipment, and mobile hydraulic systems. It has a moderate viscosity and offers sufficient film strength without losing responsiveness to be used in the general-purpose applications.
Although universal, ISO AW 46 can be modified to extreme heat conditions, heavy loads or continuous-duty work, and ISO AW 68 might be a better choice. If you are looking for a premium quality ISO AW 46 hydraulic oil you can try our Atlantic X Hydraulic Oil AW 46.
ISO AW 68: High-Load and Hot Conditions
The ISO AW 68 has a better thickness that provides stronger lubrication films for high pressure, heavy load, or high-temperature systems.
It is usually found in hydraulic presses, construction machinery, steel plant machinery and in older hydraulic systems where the wear of the pump is an issue. Its increased viscosity keeps the system safe because it protects itself when heated to minimize wear and internal leakage.
The trade-off comes at the cost of lower flow at low temperatures and slightly slower machine response. ISO AW 68 is best suited when the operating temperature is high, the loads are heavy or the constant operation is likely to thin lighter oils. If you are looking for a premium quality ISO AW 68 hydraulic oil you can try our Atlantic X Hydraulic Oil AW 68.
ISO AW 100: Severe-Duty Protection
The heaviest of the common grades of hydraulic oils is ISO AW 100 which is used in extreme-duty systems. It boasts the greatest film strength of large presses, mining equipment, offshore equipment, and other heavy hydraulic loads.
The grade guard against the high pressure and high temperature parts, but may cause low speed systems or cold environments to respond slowly. It should not be used without recommendation by the manufacturer or in any case when it is necessary to provide heavy-duty protection. Our Atlantic X Hydraulic Oil AW 100 is a premium quality ISO AW 100 hydraulic oil that you may consider trying.
How to Choose the Right Hydraulic Oil for Your Machine
The machine type, load, operating environment and temperature must be considered to choose the right ISO AW grade.
Light-weight, rapid movements (precision CNC, small presses) → ISO AW 32.
General industrial equipment (standard press, forklifts, injection molding) → ISO AW 46.
Systems with heavy loads or high temperatures (steel plant presses, construction machinery, operating older constant-duty machines) → ISO AW 68.
Severe-duty, high-pressure, high-temperature equipment (large industrial presses, mining, offshore hydraulics) → ISO AW 100.
The ambient temperature affects selection: in cold start, oils with lower viscosity are better, in hot climates, those with higher viscosity. Another problem is the age of the machine: the older machines with the parts that are worn out may be improved to slightly higher viscosity to maintain pressure and reduce internal leakage.
Importantly, it is essential to start with the recommendation of the manufacturer. Adjust to the real-world conditions within prescribed bounds.
Beyond Viscosity: Additives and Oil Types
It is not just a matter of viscosity. Anti-wear (AW) hydraulic oils are oils that are filled with additives that prevent friction and wear in pumps, gears, pistons, and valves.
HM and HLP classifications are hydraulic oils with anti-wear properties, resistance to oxidation, rust protection and thermal stability. The right choice of ISO AW grade and additive package guarantee maximum protection and performance.
Maintenance and Oil Life
Even right oil must be checked. The oil is corroded by heat, dust, water and metal particles. Oil may require replacement, and signs of this include: dark or cloudy color, burnt odor, foaming, sluggish operation, noisy pumps or metal particles in analysis.
Regular changes in oil and oil analysis are necessary. This will keep your hydraulic system safe and your hydraulic system performing at its best.
Trust Atlantic Grease and Lubricants
Atlantic Grease and Lubricants provide superior-quality ISO AW 32, 46, 68, and 100 hydraulic oils for industrial, mobile, and heavy-duty applications. Our team helps the customers in choosing the right grade to use in their machines based on the requirements of the manufacturers, load, temperature and working environment.
Collaborating with Atlantic Grease and Lubricants, you will receive professional advice, quality products, and security as your hydraulic systems will work well and will last much longer. Get in touch with us to locate the perfect hydraulic oil for your machine.
