Finding the right part
The difference between genuine, OEM and aftermarket parts
What genuine parts, OEM-equivalent parts and aftermarket parts are, where the price difference comes from, and which parts you should never skimp on.
It is normal to hear three different prices for the same part. If you know where the difference comes from, you will neither overpay nor buy a risky part just because it is cheap.
Genuine parts
A part sold in the car manufacturer's branded box. It is usually available from dealer workshops and genuine parts sellers. Its quality is known and its price is the highest.
OEM equivalent
Car manufacturers do not make most of their parts themselves; they buy them from companies such as Bosch, MANN, TRW, Sachs and Valeo. These companies also sell the same part, or one made to the same standard, under their own brand. The box is different, the price is usually lower than genuine and the quality is close to genuine. This is the category many mechanics prefer.
Aftermarket
Parts made by companies with no link to the car's manufacturer. Some are very good, some are very poor. The price is the lowest; the quality depends on the brand.
What to buy for which part
- Safety parts (brake pads, discs, brake hoses, ball joints, control arms, steering parts): Choose genuine parts or well-known OEM brands. Look for ECE R90 approval on pads and discs.
- Service parts (filters, spark plugs, belts): OEM-equivalent products from well-known brands are often the best value for money.
- Body and plastic parts: Aftermarket products can be fine; watch out for fit and colour differences.
About used parts
Parts taken from scrapped cars can sometimes do the job, but they are not recommended for wear or safety parts such as brakes, suspension and timing belts, because their history is unknown.
FAQ
Is an OEM part genuine?
An OEM-equivalent part is sold under the own brand of a company that supplies the car manufacturer or makes parts to the same standard. The box is not the carmaker's, but the quality is close to genuine.
Can aftermarket parts be used on a car under warranty?
For cars under warranty, the warranty terms state which parts and which workshops are accepted. Read the terms; if you are unsure, ask your dealer in writing.
This guide gives general information. Torque values, fluid quantities and service intervals vary by vehicle; follow your owner's manual. If you are unsure about safety-related work, ask a mechanic.