A customer brought their vehicle into the dealership for servicing and it needed new brake pads. They asked what would be the cheapest option to replace them. We said that we recommended Mazda OEM replacement pads but it would be cheaper to buy some after-market pads. They then asked why buying Mazda OEM brake pads would be more expensive. After answering this question, we thought it would be helpful information to include in a post for anyone else who would like to know.

Car manufacturers manufacture accessories and replacement parts for their vehicles. The great thing about OEM parts such as these is that they are manufactured by the people who made the vehicle, so they are aware of the most important factors to consider in their design. This allows them to have better longevity, safety and fit.
Similar to how the original watch maker knows exactly how their watch works and thus knows exactly how to fix it, original equipment manufacturers know the exact specifications of the part and how it fits into the rest of the vehicle’s machinery. This is often the safest option when replacing a part as well as having a factory trained technician fitting the part. They have been trained by the manufacture and are familiar with your vehicle and its operation. In summary, the OEM parts and the factory technicians fitting the parts are the best fit for your vehicle.
This is not to say that there are no advantages in using aftermarket parts. Due to the wide variety of parts manufacturers it is possible to find parts that are at times better quality than OEM ones. For example, a company that specializes in winter floor mats could make ones that are superior in quality but cheaper because that is their specialty. Also, an aftermarket more expensive winter mat set could be of lower quality. Price is not always a sign of quality and fit. For example, OEM winter mats have hooks to hold them in place to ensure they do not get tangled with the accelerator pedal and aftermarket ones may not. In this case safety is jeopardized so cost is not important. The best thing to do when buying an aftermarket part is to do your homework.
Research, read reviews and even ask mechanics you know about which brands and products are of good quality and fall within your budget.
One of the reasons OEM parts are often more expensive than after market ones is because they are often covered by a warranty (often for 1 year) while aftermarket parts often have shorter warranties or none at all. So despite the slightly higher price OEM parts come with the piece of mind that should something go wrong with your part, the original equipment manufacturer will be able to repair/ replace it for you under its warranty.

So when it comes to replacing a part for your vehicle the OEM part is the safest option. Remember to do your homework if you decide to not get OEM parts.