Automotive spare parts are broadly divided into two types - Original Equipment Manufacturer (OEM) and aftermarket parts. OEM parts are made by the original vehicle manufacturer or an authorized manufacturer gets exclusive rights and specifications from the original company to make the automotive parts.
Aftermarket parts are not manufactured by the vehicle manufacturers. Aftermarket parts are designed in such a way that they fit into two or three similar automobile models. Though OEMs and aftermarket parts look similar, their design and quality is different.
To understand the difference between OEM and aftermarket spare parts let us compare various parameters.
• Quality: OEM parts are of assured quality as they are genuine and are manufactured according to the vehicle manufacturer's specifications. Unless, the original manufacturer approves them, the auto parts cannot be manufactured. Further, as they are released in market with the original brand name, the manufacturers have long-term incentive to protect the reputation of the brand and thus maintain the quality as per the standards.
Independent manufacturers buy rights to manufacture and supply original parts. On the other hand, aftermarket parts are not made by the OEM, they are not original. That doesn't mean that aftermarket products are of sub-standard quality. They also perform well and at times they are of the same quality as the original or OEM parts.
• Variety: When it comes to variety, we have to admit that aftermarket parts are available in wide variety, as dozens of companies manufacture them in different variations. They are designed to fit different auto makes. However, this overwhelming selection may sometimes confuse the customer and may increase the likelihood of getting a bad quality product.
OEM parts are manufactured by only some companies. They are designed to fit in a specific automobile. So, the variety may not be that great. However, this limited variety helps the user to choose the exact spare part for the automobile.
• Cost: OEM parts are expensive when compared to the aftermarket parts. Aftermarket manufactures often succumb to the price pressure and tend to reduce the prices to make the products viable. In this process they may compromise on the quality of the products.
But, OEMs, bearing the responsibility to protect the brand image of the company will not manufacture sub-standard parts. Thus, their pricing is almost close to the original parts. Though they are expensive it's worth investing because of their promising quality and durability.
• Warranty: Warranty is the major difference between OEM parts and aftermarket parts. OEMs generally back up their products with at least one year warranty. But the after-market manufacturers in order to keep the costs down will not provide any warranty for the parts.
• Usability: OEM parts are similar to the original parts and will exactly fit the automobile. As aftermarket products are designed to fit a variety of models, one has to check if it fits their automobile. In some cases, they may require slight/major modifications before installing to make them fit correctly and operate properly in a specific vehicle.
• Availability: OEM parts are available at authorized dealerships. One has to go to a dealership to buy. Whereas aftermarket products are available at different places like auto stores, gas stations, mechanic/repair shops, etc. leaving you with more options to make a purchase.
• Safety and security: The use of low quality material may increase safety issues with aftermarket parts. But OEM parts are reliable as the manufacturers never compromise on the quality factor. If the aftermarket parts are of low quality or less expensive, then they may wear faster. So, you need to check them periodically to avoid safety issues.
To conclude, aftermarket parts are made by local manufacturers and they don't meet the standards of the OEM parts. You can find two varieties in aftermarket parts - good quality and low quality, but it is not the same with OEM parts, they are of high quality. If you can figure out the brands that offer good quality aftermarket parts with lot of price variation compared to OEM parts, that you can save money. However, if the price difference is negligible it's better to opt for OEM parts.