Which Hydraulic Oil is Right For Your Machine?

It pays to be picky when it comes to choosing a hydraulic fluid. Sure, your equipment may run on a less-than-optimal viscosity of the hydraulic fluid; however, not using the best lubricant for your machine may shorten its life in the long run. Here’s the info you need to pick the best hydraulic oil for your machine.

Choosing the Right Grade

You can choose between monograde and multigrade hydraulic oil. Monograde oil is generally used in machines operating in a narrow, moderate temperature range. Machines that will not need to run in freezing or high temperatures can operate with a monograde oil. This type of oil is less expensive than a multigrade oil and will prevent loss of viscosity due to VI improver shear down.

If you’ll be operating your machine in freezing or very high temperatures, however, you’ll want to use multigrade oil. Multigrade oil is manufactured to maintain viscosity in varying temperatures. Don’t try to get by using monograde oil if you’re operating in high heat or freezing cold.

Detergent Fluids


The good thing about hydraulic fluids is that they disperse debris and sludge. This will keep contaminants out of your components. There are a couple drawbacks, however, detergent oil will emulsify water, meaning that your oil will not last as long. The presence of water in your oil can also cause corrosion. Contaminates will also need to be filtered out — they won’t precipitate out into your reservoir.


Anti-wear additives help maintain lubrication as the oil approaches boundary conditions. The most common antiwear additive is zinc dialkyl dithiophosphate (ZDDP). Some drawbacks to ZDDP are that it can break down some metals and reduce filterability. However, a stabilized form of ZDDP eliminates these issues.

For more information on finding the best hydraulic oil for your machine, check out these articles.