Oil Seals Overview – Sealing solutions for all applications

What is an oil seal?

Oil seals, often called a rotary shaft seal or grease seal, closes the gap between stationary and moving components in mechanical equipment — most often rotating shafts — helping prevent lubricant escape and stopping harmful materials, such as dirt, from moving in through the clearance. Oil seals are most commonly used in gearboxes, hydraulic cylinders and related components.

Main Elements of an Oil Seal


The Oil Seal size is typically specified by three common dimensions: the rotating shaft diameter (sometimes referred to as the inside diameter of the seal), the housing bore diameter (sometimes referred to the outside diameter of the seal), and the width (thickness) of the seal itself. Because of an oil seal’s purpose, size is critical. The inside diameter of Oil seal must always be slightly smaller than the shaft diameter in order to seal lubricants inside and prevent harmful contaminants from entering.

At Global O-Ring & Seal, we offer customers true Metric and Inch oil seal size classifications. Why is this so important? Because equipment used all over the world requiring oil seals is manufactured according to true inch or metric sizes and anything less than a true measurement would have a lasting negative impact on the application. We’re the All-Around Better choice in providing oil seals,  providing peace of mind that the oil seal size is right for any application located anywhere around the world. Need a specific size oil seal? View our live inventory here or speak with one of our sales team members who are knowledgeable in oil seals applications!


Which seal is right for you?

Our oil seals come in a variety of materials suited for every imaginable application and environmental condition, including: chemical resistance, low compression set, resistance to high and low temperatures, elasticity, resistance to ozone and weathering, cost, and resistance to water. To learn which oil seal is best for your equipment, review our Oil Seal Material Selection Guide.


Not sure which oil/grease seal style to use? No problem. Just review our comprehensive Oil Seal Style Guide here to decide which oil seal will work best for you. If you still need help, contact us and we’ll work with you to choose the right style.

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