When doing maintenance on your car or any engine that uses oil for lubrication, it is beneficial to know the various product numbers of any oil seals you may need. This makes the ordering process more streamlined and allows the necessary seal to be in your hands as soon as possible so you can get back to work. To get the product number, all you need to know is the size of the shaft you need to seal.
Measure the diameter of the shaft in inches. An exact measurement can usually be found in the official specifications or service manual of the machine you are servicing.