To maximize productivity and component life, equipment
manufacturers machine component parts to precision levels.
A component’s sensitivity to contamination determines how
clean the oil needs to be.
Here’s a good rule of thumb: Oil needs a cleanliness level to protect the tightest machine clearance on your equipment.
So, if a proportional control valve on a hydraulic system is the tightest clearance on a piece of equipment and the control valve component manufacturer requires an ISO Cleanliness Code of 16/14/12, then an ISO Cleanliness Code of 16/14/12 would be the target level for new oil.
Most equipment manufacturers and individual component
manufacturers set ISO Cleanliness requirements for oils.