One would think that new hydraulic oil that is in a sealed container would be clean. However, surprisingly, and somewhat disappointingly, this is not always the case. Oil can easily become contaminated during the process of distribution. Although some oil is packaged within the factory or blending facilities, some oil may be sent out to bulk oil distributors in containers such as a railway tanker or a tanker truck. Although there are oil dedicated tanker systems in existence, they are not allocated to specific products. For example, motor oil may have been in a tanker before hydraulic oil is shipped in it. At local distributors, oil will be stored at bulk storage facilities and then decanted to plastic bottles and drums with plastic seals added. It’s at this point that hydraulic oil could meet with cleaning products that were used in drums to prevent contamination. Also, the oil will have been handled several times and therefore it’s more likely to have been contaminated. If you buy in bulk and it’s delivered to your facilities in a container, there’s a chance that your hydraulic oil will pass through pipes and nozzles that were not flushed very well before use. They may have had some remnant of the previous products in them, such as 15W40 motor oil. This could end up in your storage facilities, and ultimately in your hydraulic system. Now it’s a question of how clean your storage and dispensing facilities are. Are they sealed so as not to allow particle contamination? Are they exposed to extreme temperature level changes or too external elements or flushed with water from a hose? Of course, you should really know some of the answers to this, but it’s quite likely that you don’t. However, you can take an oil particle count analysis to measure your contaminants. You could be surprised at the results and how they differ from what you expect.