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What Affects Oil in a Hydraulic System

Inefficient oil flow isn’t just slowing down your hydraulic system; it may be costing you thousands of dollars.

A hydraulic system with improper oil flow works harder, takes longer, consumes more, pollutes more and costs more.

Fortunately, preventing oil flow problems is as simple as proper maintenance and oil choice. Apply these three tips to improve oil flow and start saving money (and the environment) right away

Pick the Right Oil For Your Operating Climate

The biggest factor linked to oil flow is viscosity. And the biggest factor in choosing your oil viscosity is the range of temperatures your system will be operating in.

If the oil viscosity is too high, oil flow and lubrication are hindered when operating in cold temperatures. This could result in wear or malfunction of your hydraulic system.

If the viscosity is too low when operating at high temperatures, your system will lose oil flow to internal leaking. This can also hinder lubrication and cause wear.

Since most hydraulic systems will have to operate in the extreme temperatures of winter and summer, your best bet is to use a multigrade oil as it is designed to operate efficiently in both extremes.

Because multigrade oil is more expensive than monograde, some people use a different oil for different seasons. But multigrade oil has been tested and proven to provide average savings of 4.8% in the summer and 20.1% in the winter, despite it’s higher purchase cost. Another study found that multigrade oil can save you $10,000 for every 1,000-hour drain interval.

Proper Maintenance of Your Hydraulic System

This may seem obvious, but don’t be passive. Neglecting maintenance is the second easiest way to lower flow rates and, therefore, operating efficiency.

Check your system for kinked or dented oil lines, leaks, cracks, clogged parts or any parts that need replacing or cleaning. When was the last time you checked?

Change your filters regularly. A dirty or clogged filter will restrict oil flow.

If you want to be extra efficient, don’t change filters according to a schedule. If you do, you may be replacing them too often (costing you more for filters) or not often enough (reducing the life of your system’s parts with dirty oil).

Instead, use a clogging indicator to monitor pressure drops across the filter to find out exactly when it needs changing.

This principle applies to changing oil, too. Never dump that oh, so expensive oil according to a timetable unless you enjoy throwing money away. Only change the oil when you’ve analyzed it and confirmed that the base oil is degraded or the additive package is depleted.

Reduce Air Entrainment

Lastly, air bubbles trapped in your oil can hinder oil flow because aerated oil is harder for your system to pump.

Air entrainment can be caused by system leaks, splashing or improper bleeding when adding oil, and contamination. Mostly, air entrainment can be prevented with proper maintenance. But it can also occur on its own when dissolved air inherent in hydraulic fluids is released during operation.

If entrained air is affecting your oil flow, a bubble removal device can be used to deaerate the oil.


Improving oil flow isn’t difficult. Practice proper maintenance, use multigrade oil and start saving money.

Need more help? See what our team of experts can do for you. Or, better yet, let us know exactly how we can help.

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