Hydraulic Oils Have Similar Goals But Different Chemistries

Hydraulic oil is a fluid that has several functions. It serves as an energy transfer or power transmission medium, lubricant and sealant. Also, it is a fluid that cools the equipment and carries contaminants away.

Hydraulic systems allow us to do everything from jacking up our cars to move mountains.   They require a pump, a hose, valves, and actuators. Add hydraulic oil and you’re in business. Choosing the proper oil for a given system is as easy as opening the owner’s manual and looking at the manufacturing recommendation. It’ll provide the performance specifications the oil must meet and the correct viscosity for ambient temperatures.

There are multiple types of hydraulic oils, they must all provide the following:

  • Good wear protection
  • Prevent corrosion
  • Meet minimum/maximum viscosity requirements

Where they are not the same is their chemistries. Some are designed for a specific purpose and must be used under certain circumstances to comply with the law or machine performances.

Zinc Anti-wear hydraulic oil

Zinc-containing hydraulic oil is the most common type. It’s less expensive than other hydraulic oils but provides excellent wear protection due to its zinc additives. It has a long history of providing great service in all kinds of applications. However, zinc is considered a heavy metal and pollutant and some applications have moved away from it in recent years. Some applications are sensitive to even small amounts of zinc, like high precision computer numerical control (CNC machines), which require non-zinc oil due to zinc build-up affecting accuracy over time. Zinc-containing oil provides good cleanliness for most hydraulic applications.

Non-Zinc Hydraulic oil

Also referred as “ashless”, nonzinc oils use newer technology and provide the same level of performance without zinc. This oil is more expensive and harder to find, but is becoming more common. They eliminate heavy metals to reduce environmental impact while reducing deposits in some precision applications. Mixing zinc and non-zinc oils may lead to compatibility issues in the form of high foam or filtration. Flush the system to avoid switching oil types.

Bio-degradable Hydraulic Oil

Environmental protection being a concern, biodegradable hydraulic addresses these concerns, bio-degradable hydraulic oils degrade into harmless substances in the presence of sunlight and microbes. Biodegradable oils are  derived from vegetables stocks, canola, sunflower or rapeseed.  Polyalphaolefin (PAO) or esters are also used. These oils can be designed to provide outstanding hydraulic performance for their intended applications.

Where Bio-degradable Hydraulic Oils Are Used

  • Marine applications where vessel General Permit guidelines regulating vessel discharges must be followed
  • Army Corps of Engineers projects: dams or dredging
  • Helps reduce environmental harm in the event of leaks or minor spills.

When choosing the right oil, understand that “one size” does not fit all. Ambient temperature, viscosity requirements, and environmental impact are concerns. Amsoil has a complete line of hydraulic oils for your needs.