There are a lot of misconceptions regarding the parts that go into BMWs during Service and production, especially when it comes to OEM Parts vs. Aftermarket Parts. As a consumer, I feel it is pretty important to know what these terms actually mean, and how they affect the longevity of your BMW. I field an amazing amount of calls by potential customers concerned with OEM parts going into their BMW, all the while many do not understand what OEM actually defines when it comes to the description of a particular BMW part. So . . . let us expose a few terms, what they actually mean, and how they affect your BMW.
BMW Genuine Parts
BMW Genuine Parts are those parts which have been purchased from a BMW Dealer. This does not necessarily mean that BMW produced the part, rather that they are a re-seller of parts that have been produced for them. Some Genuine parts are produced by BMW but they are usually limited to interior trim pieces, sheet metal, bumper covers, wiring, etc. Most other parts are produced by other companies for use in BMW repair or production.
The Good – Genuine Parts should be just as good as the part that failed you, and the part will also be backed by BMW’s warranty policy for parts which is usually 12k miles or 12 months.
The Bad – Genuine parts are expensive, and they aren’t always the best available. Genuine Water Pumps are of great concern due to the plastic that is used for the impellar of the pump. This plastic has been prone to failure, while many aftermarket water pump manufacturers have eliminated this plastic in favor of all metal pumps.
OEM Parts
OEM stands for Original Equipment Manufacturer, plain and simple. It does not mean ‘BMW Genuine Part’ but is basically the same or sometimes better. During the production, BMW, like many corporations, outsource to many different companies to produce parts for them during assembly. BMW puts together a mechanical design specification and quality requirement and sends a bid request off to numerous corporations. These corporations submit bids and are granted a production contract from BMW. As you might expect, this is big business. Therefore, your spark plugs are not made by BMW, they are made by NGK or Bosch. Brake pads are not made by BMW, they are made by Pagid or Jurid. Shocks are not made by BMW either, instead they will contract with Bilstein or Sachs. BMW didn’t make your alternator either, chances are that Valeo or Bosch made that instead. But these are all OEM suppliers for BMW.
The Good – You can get what is basically the same part in your car without having to pay hefty prices
The Bad – The term OEM gets thrown around A LOT by parts suppliers. Sometimes you need to know if the part is actually an OEM Supplier rather than “OEM Quality” For the most part, if you see “OEM Quality” or, my favorite, “Meets or Exceeds OEM Standards” the part is probably a piece of junk that won’t last.
After-market Parts
An After-market part is a part that has been produced outside of an OEM production contract. For instance, Sylvania has the contract for turn signal bulbs on an X5, but on eBay you can find hundreds of other bulbs that can be used in place of the original bulb. This is probably the largest category of parts available to consumers. After-market parts cover everything from tires to turn signals that have not been produced under contract from BMW. Some after-market parts are great, while others leave little to get excited about. It is important to do your homework and look for reviews when entering into the aftermarket parts arena.
The Good – Options, options, options. The reason aftermarket parts is such a large category is due to the fact that consumers like to have options and like to customize. There are also a lot of exceptional upgrade parts available such as shocks, tires, lights, etc. If you know how to navigate this world of parts, you can really find some incredible products for a vast array of applications.
The Bad – There’s a lot of junk out there for sale. Remember that while there are some good deals and products on the market, you usually do get what you pay for.
Chris Keefer
5836 Autoport Mall
San Diego CA 92121
858-455-5836
BMW Service Blog 
Nice post Chris…one question, why don’t replacement batteries seem to ever last as long as OE batteries? Just curious….thanks for the great blog!