OEM vs. aftermarket parts vs. customization

A quick guide how to choose the right spare part type

The spare parts dilemma

If you have an old or a new vehicel at some point in the car lifetime there will be parts to be replaced. This can be caused by several reasons like worn out parts, broken components or just the wish to change to something more indivual. I want to give you a quick overview of which strategy to choose for which purposes and also which type of parts.

Channel comparison

There are several ways how to purchase spare parts - following I will call those "CHANNELS". The table sums up the main properties of the 4 channels available and compares them briefly. Below you can find a more detailed version for each purchasing type. It is important to note that this is only the first half you need to consider for your choice of channel.

OEM spares

OEM is the abbreviation for Original Equipment Manufacturer. Basically all the spares are manufactured by the OEM or a contracted Tier1 companies. These parts are designed and tested according to quality standards of the brand. Although these standards ensure mostly long lifetime and perfect fit they come with a price which is more than people normally want to pay. A neat option to reduce the price is buying used OEM parts as spares. Doing this it is very important to take care of the state of the part. It can help to take a mechanic when going to a used spare parts dealer or a scrapyard.

Aftermarket spares

Aftermarket spare parts are not manufactured by the OEM or a contracted Tier1. These parts are mostly reverse engineered to serve the same purpose as the original part. It is important to mention that those parts are only similar to the OEM part and don't undergo the same quality tests which can lead to fitting issues and lower quality. Another drawback can be that different manufacturers have different (but similar) products what can confuse you chosing the right component. On the other hand these products are mostly way cheaper than the originals and offer you great savings when you find the right one in the right quality.

Customized spares

When talking about customized car parts many people think that this is only something for car enthusiasts who want to tune their vehicle to top performance or change to an individual design. This might be true for a certain percentage but this channel also covers other needs: E.g. there are OEM parts which tend to break because of design failures. Those can be improved by some little adjustments to make them more durable. There are also parts of old vehicles which are neither available on the OEM spare market nor on the aftermarket. The price range is somewhere in beetween OEM and aftermarket which is quite clear due to low production volume and high flexibility.

Now we know about the main differences of the spare part channels. Considering the quality aspect of those we also need to have a look at different component groups in our vehicles. The table below shows an evaluation of the channels for different components in our car which is mainly based on security and allover lifetime of the car. E.g. you don't want to have a product with potential lower quality standards and test in your braking system. Or imagine you change a worn out part in the engine which breaks after 2 months and causes an engine damage. It might have been cheap in the first place but will cause a lot trouble afterwords.

Recommended source by category

Recommended source by part category

How to chose the right channel for my part?

Combining the details above we have a more clear picture about when to use which purchasing channel for our spare parts. Below you can find a diagram which ullistrates this:

How to choose the right spare part channel

OEM (new/used)

    • Functional and security parts

    • High price and quality

    • No changes (improvements) possible

    • Car age: New - medium

    • Available

      • Car manufacturer


  • All parts except of security and high functional parts

  • Low price comes often with lower quality

  • No changes (improvements) possible

  • Car age: New - youngtimer

  • Available

Customized parts

  • All parts except of security and high functional parts

  • Medium price and high quality

  • Customer driven changes possible

  • Car age: All

  • Available