OEM automotive parts definition

An automobile part may carry the designation OEM (original equipment manufacturer) if it is made by the same manufacturer and is the original part used when building and selling the product.
A replacement part specifically approved by the brand owner of the end product may also reasonably be referred to as OEM.

You may have heard parts companies sales staff say "we have an OEM part in stock." This refers to a part that is made by the same manufacturer as the genuine part you would receive from you local automotive dealer. Believe it or not most carmakers do not manufacture and produce the parts they use to build their automobiles. Most carmakers use outside independent companies to help them design the parts used in your car. Carmakers then put them in their own boxes with their logos to make you believe that you are buying a part that the carmaker made itself. After a certain time frame the actual manufacturers of these parts are allowed to sell them to other wholesale distributors for resale. This time however they come packaged in a box with the name of the actual manufacturer of the part. Its not an inferior part its just put into a different package and usually sold up to 70 percent cheaper than the dealer originally sold it for and continues to sell. In most cases the part will be identical with the exception of the packaging.