More info on Original Equipment Manufacturer.

1. An OEM part is a stock part (opposite of custom part or aftermarket part). This is the definition mentioned above.

2. The OEM is the company that originally made the component. For example, the A12 carby was made by Hitachi. Hitachi was the OEM. But Datsun sold and warranteed that part. Normally, the end customer won't have any contact with the OEM, but instead deals with the producer of the finished package.

3. Or just the opposite: The OEM is the company that buys various parts, produces a product and puts their brand name on it.

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