The Reliability Files

Get More From Hydraulic Systems In Wide-Operating Temperature Applications

EP Editorial Staff | September 4, 2011


As you probably have noticed, today’s hydraulic systems are much smaller, run at more extreme temperatures and work harder than ever before. On top of those challenges, many hydraulic systems have to operate through a wide temperature range.

Finding the right hydraulic fluid can make a big difference in ensuring peak performance throughout extreme temperatures and conditions as well as helping to reduce downtime and extend drain intervals. Fortunately, just like our hydraulic systems, the hydraulic fluids we use in them have come a long way in terms of performance. Knowing what to look for is key to getting the right fluid for your system needs.

A number of important factors come into play when choosing the right hydraulic fluid. Of course, you want to make sure the fluid you choose meets OEM specifications and adheres to best practices. You also want to ensure you have a strict maintenance and service protocol to keep your equipment running at its best.

Click the image above
to view Petro-Canada’s
full-size advertisement

The importance of a high viscosity index…
One important characteristic to look for in a hydraulic fluid is the Viscosity Index (VI)—an important indicator of the oil’s ability to resist changes in viscosity due to temperature variations. The higher the VI, the less the oil’s viscosity will be affected by temperature changes.

For hydraulic equipment that is subject to a wide range of operating temperatures, high-VI fluids are essential to reduce internal pump leakage, eliminate sluggish operation and increase overall operating efficiency.

  • At low temperatures
    At extreme cold temperatures, you want your hydraulic fluid to have excellent fluidity, which relates to the right viscosity based on temperature. This allows the oil to flow more readily. If the oil is too thick at cold temperatures, it simply won’t flow properly and startup may take longer.
  • At high temperatures
    High-VI fluids maintain viscosity at high temperature better than monograde fluids of the same KV40C. A premium-performance, high-VI hydraulic fluid can provide extra protection during periods of extreme high temperatures, which can help minimize wear on equipment and bring greater peace of mind when equipment is running under heavy loads and high pressures.
    A typical hydraulic pump can convert up to 20% of its horsepower into heat, so most fluids may run at elevated temperatures which also present challenges to hydraulic fluids. At extreme high temperatures, you don’t want your hydraulic fluid to become too thin. You need the optimal viscosity—meaning the ideal viscosity for the operating temperature—to optimize efficiency of the hydraulic pump.

Return on Investment
HYDREX keeps your operation running smoothly. It lasts up to three times (3X) longer and offers up to two times (2X) better wear protection than the leading hydraulic oil brand. HYDREX also resists oxidative breakdown—which prevents harmful sludge buildup. So, when you use the right fluids in conjunction with your preventive maintenance program, protecting your investment isn’t as daunting as you may think.

Petro-Canada Lubricants Inc.
Mississauga, ON, Canada

For more info, enter 261 at




View Comments

Sign up for insights, trends, & developments in
  • Machinery Solutions
  • Maintenance & Reliability Solutions
  • Energy Efficiency
Return to top