100% Employee Owned, Founded 1954

100% Employee Owned, Founded 1954

100% Employee Owned, Founded 1954

New Hydraulic Oil is NOT Clean Hydraulic Oil

Richard Tatum | December 1st, 2015

In some of my latest blogs I have discussed how to determine what oil cleanliness your system needs, as well as where and what types of filters that you need placed on your system in order to achieve these goals. Here is another tip that you must always take into consideration when putting new fluid into a hydraulic system. New hydraulic oil does not mean that it is clean hydraulic oil. Hydraulic oil in the barrel can be very dirty and can sometimes be saturated with water.

How Dirty Is New Hydraulic Oil?

New hydraulic oil straight from the drum has a typical cleanliness level of ISO 4406 23/21/18. From what we have learned in my previous blog “Selecting a Filter: 3 Steps to Better Mobile Hydraulic Performance” you can see that this is 16-64x dirtier than what most hydraulic systems require (each 1 number increase in the ISO code is double the contaminant level for that micron size)!! Looking at it another way, a 25 GPM pump operating continuously in hydraulic oil at 23/21/18 will circulate 3,500 pounds of dirt to the hydraulic system’s components each year. That is crazy!

How to Clean New Hydraulic Oil

To add hydraulic oil, and not the dirt, always filter new oil prior to use in a hydraulic system. This can be done a number of ways, but the most common is to use a filtration cart or kidney loop filter in your reservoir. Schroeder makes an exceptional filter cart that can not only remove dirt particulates from new oil, but also water, if that is something that is needed to be done. These carts are really a good bang for your buck as they range from relatively low cost to expensive, depending on what you are trying to accomplish. Additional good news is that if you are already running Schroeder mobile filtration on your machine, then there is a good chance that you can use the same filter element that you already use, thus reducing inventory parts. You can find more information on these carts here: Schroeder Industries. Below is an example of the Schroeder media that will get you the ISO ratings that you require.

Another way to pre-filter your hydraulic oil is by pumping the oil into the hydraulic reservoir through the system’s return filter. The easiest way to do this is to install a tee in the return line and attach a quick-connector to the branch of this tee. Attach the other half of the quick-connector to the discharge hose of a drum pump. When hydraulic oil needs to be added to the reservoir, the drum pump is coupled to the return line and the oil is pumped into the reservoir through the return filter. Another benefit of doing it this way is because spills are avoided and the ingress of external contamination is prevented.


While many people don’t even think about filtering new oil, it is very important to get clean oil into the system. It is much easier to prevent dirt from getting into a system by using precautionary measures than it is to remove dirt from a hydraulic system. Once dirt is ingressed, it is very difficult to get the system clean. This is why we must take the time to do it correctly. While this takes more time and money up front, the machine will run and operate longer with fewer maintenance issues in the field. This will save you money!

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Mobile Technology Demonstration at ICUEE 2019

Wade Wessler| August 29, 2019 We would like to introduce ourselves at the upcoming ICUEE 2019 Show in Louisville, KY, October 1-3, 2019 (Booth #1054). Here are some things that you will see on our Cross Company technology truck: Emerging technologies Cross Company mobile IoT telematics solution Vehicle electrification – flywheel mounted PMAC generator, PMAC

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