You may have heard other parts companies and even a sales staff say "we have an OEM part in stock." This refer to a part that is made by the same manufacturer as the genuine part you would receive from your local automotive dealer. Believe it or not most car makers do not manufacture and produce the parts they use to build their automobiles. Most car makers use outside independent companies to help them design the parts used in your car. Car makers then put them in their own boxes with their logos to make you believe that you are buying a part that the car maker made itself. This could not be further from the truth. How do these parts become available to companies to be sold to the general public? 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.
Aftermarket parts are just the opposite of OEM parts. These parts are produced by companies other than the original manufacturer but are made to fit and perform as well as the original. Aftermarket companies buy the rights to produce these parts and supply them to the same wholesale distributors as the OEM parts. These parts are generally produced with the same machinery and materials but because they were not designed in the same manner the part may have minor differences in appearance and feel. Some aftermarket companies, upon getting the right to produce a part, may indeed find a way to improve a part by redesigning it. This results in a better part and quite possibly a less expensive one. They are a variety of high quality aftermarket parts that can be purchased and live up to all the expectations of the original at a much lower price.
In both cases, OEM and aftermarket parts, the part should serve its purpose and perform the function it was designed for. As the car owner it is your choice that ultimately decides which part is chosen. By knowing these few things you can more easily determine which is best for you and your car. Remember in most cases buying a part from the car maker or dealer does not mean you get a better quality part. The same part can be purchased at a fraction of the cost still give you that same piece of mind feeling.
Text courtesy from www.ThePartsBin.com