The time has come to replace a part, and you have three options: OEM, aftermarket or used. The price gap between the cheapest and most expensive option can be enormous, and drivers rightfully wonder whether a pricier part actually means a better one. The answer is not always the same - it depends on which part you are replacing, what car you drive, and what quality the replacement manufacturer delivers.
Three categories of parts we see in the workshop
An OEM part (often labeled as such because it was made by the same manufacturer that supplies the car factory) comes in a box with your car's brand on it. It carries the vehicle manufacturer's marking, the catalog number is from their system, and the price reflects that branding. This part is identical to the one installed at the factory, but costs more because it goes through the vehicle manufacturer's distribution network. For some parts, the markup can be double or even triple compared to aftermarket.
An aftermarket part (a replacement part that does not come in the original brand's box, but may be of the same or similar quality) is made by independent companies. The key thing to understand here is that many reputable aftermarket brands actually produce the exact same parts that go into the factory. Bosch, Mann, Mahle, TRW, Lemforder, SKF, Sachs, LuK, NGK, Denso - these are all companies whose parts sit inside the original boxes of many car manufacturers. When you buy their part in aftermarket packaging, you are getting the same product at a noticeably lower price. The difference is literally the sticker on the box.
A used part is taken from another vehicle, most often from a car damaged in an accident or sent for scrap. It has its purpose and can significantly reduce costs, but everything depends on what you are buying and what condition the part is in.
Where you should not cut corners
There are parts where saving on quality can cost you far more than the price difference. These are primarily safety components that directly affect braking, steering, and engine integrity.
Brakes top the list. Pads, discs and brake hoses must come from a reputable manufacturer. Cheap pads of unknown origin have a shorter lifespan, weaker stopping power in the wet, and wear down discs faster. TRW, Brembo, ATE, Ferodo, and Textar are brands we trust in the workshop, and their prices are considerably lower than OEM parts in the car manufacturer's box. We would never install nameless pads on a customer's car, no matter how cheap they are.
Suspension is another category where experimenting is a bad idea. Ball joints, tie rods, rod ends, and sway bar links carry the vehicle's weight and directly affect steering. A worn ball joint can cause loss of vehicle control, and a cheap replacement part can wear out in half the distance compared to a quality one. Lemforder, Meyle HD, TRW, and Febi Bilstein make factory-grade parts at reasonable prices.
The timing belt kit (or chain, depending on the engine) is the third item you should not skimp on. A mistake here means serious engine damage. If the belt snaps or skips, valves hit pistons and the repair bill is many times the cost of a complete kit. Gates, Continental, INA, and SKF are proven choices.
When aftermarket does the same job as OEM
Filters are a category where quality aftermarket brands offer excellent value for money. Oil filters, air filters, cabin filters, and fuel filters are parts that get replaced regularly at every service. Mann, Mahle, Filtron, or Hengst do the job just as well as the original filter in the car manufacturer's box, and the savings add up - especially if you service your car regularly and change filters on schedule.
The situation is similar with spark plugs and ignition coils. NGK, Denso, Bosch, and Beru supply the factories of nearly every manufacturer, so their aftermarket part is literally the same product. When someone offers you an original NGK spark plug in a car manufacturer's box at double the price, know that what is inside is the same thing.
Shock absorbers are another example. Sachs, Bilstein, Monroe, and KYB produce shock absorbers for most European and Asian models. The quality difference between their aftermarket packaging and OEM does not exist, while the price difference can be significant. The same goes for springs, bearings, and CV joint boots from reputable manufacturers.
What you should avoid are unknown brands with no reputation. If there is no recognizable manufacturer name on the box, if the price is unnaturally low compared to everything else on the market, that is a sure sign the quality is not up to standard.
Used and refurbished parts - when they make sense
A used part is a logical choice for body panels: doors, hoods, bumpers, fenders, and mirrors. These parts are not worn down by regular use, only by mechanical damage, so a piece from another car in good condition does the job just as well as new. A new OEM fender can cost several times more than a used one in excellent shape.
Glass is a similar story. Original glass from a scrapped car is always better than cheap aftermarket glass of questionable quality, especially when it comes to a windshield with a rain sensor or camera for driver assistance.
Electric motors (window regulators, wiper motors, fan motors) and some expensive electronic modules (comfort modules, BSI units, instrument clusters) are a category where a used part can save serious money. These parts usually either work or they do not - there is no gradual wear, so the risk is lower.
Where used parts do not make sense: clutch, brake pads, shock absorbers, belts, water pump. These are parts that wear through use, and you have no way of knowing how much the previous owner put them through. Refurbished (rebuilt) parts like alternators, starters, or power steering pumps can be a good choice if done by a reliable shop that offers a warranty on their work. A refurbished alternator from a trusted specialist can last just as long as a new one.
How to spot a suspicious part before installation
In our workshop, we regularly see parts that a customer brings in and that immediately raise red flags. Here is what to watch out for when buying parts yourself.
- The dimensions do not match. The part looks similar but will not sit in place without modifications. This is the most common problem with cheap no-name parts and a sign that the part was not made to original specifications.
- No manufacturer marking. A serious manufacturer always puts their name, logo, and catalog number on the part. If the part has no markings at all, that is a bad sign.
- Poor casting or machining. Uneven surfaces, visible mold lines, thin walls, and inconsistent dimensions point to cheap manufacturing with no quality control.
- Packaging without information. A box with no manufacturer name, no part code, and no compatibility information says enough.
- A price that seems too good to be true. If a part costs three or four times less than everything else on the market, the reason is almost always in the quality of materials and production control.
As a driver, you have every right to ask your mechanic which brand of part they will install on your car and why that particular one. You also have the right to ask for the old parts back as proof that the replacement was actually done. A good mechanic will not take that as an insult - they want the customer to feel confident about what they paid for.
If you are not sure which part is the right choice for your car, get in touch. It is better to ask upfront than to pay double because the wrong part was installed the first time.