There are many ways to check the quality of premium hydraulic oil. The most common way is to use a simple test kit. A hydraulic test kit includes a container, an oil sample bottle, and instructions. The process is as follows:
Fill the container with a sample of the oil you think might be faulty
Add the fluid from the sample bottle to the container
Mix thoroughly for 15 seconds
Check for bubbles in the solution
Compare your results with those on your test kit’s instructions