OEM, aftermarket or used: which car part should you buy?
For most parts you'll have three options at very different prices. None is automatically 'best' — it depends on the part and how long you plan to keep the car.
OEM and genuine parts
Genuine parts carry the manufacturer's branding and are what the car left the factory with. OEM (original equipment manufacturer) parts are made by the same supplier but sold without the carmaker's badge and markup — often the identical component in plainer packaging.
Worth it for: safety-critical and hard-to-access parts, and cars you're keeping long term. You pay more, but fitment and longevity are predictable.
Aftermarket parts
Aftermarket parts are made by third-party manufacturers. Quality ranges from excellent — established names that also supply the trade — down to budget no-name units. The trick is to buy on the brand, not just the price.
Worth it for: routine wear items like brake pads, discs, filters and suspension arms, where reputable aftermarket brands are as good as genuine for far less.
Used and reconditioned parts
A used part from a breaker, or a professionally reconditioned unit, can be the sensible choice for expensive assemblies — alternators, starters, turbos, gearboxes, body panels and lights — especially on an older car where a new genuine part costs more than the car is worth.
Buy used with your eyes open: check the seller's feedback, confirm the part number matches, and prefer sellers who state mileage and offer a returns window. Reconditioned units often come with a warranty; a raw used part usually doesn't.
A rule of thumb
Safety-critical or awkward to reach: lean genuine/OEM. Routine wear: a good aftermarket brand. Expensive assembly on an older car: reconditioned or used from a well-rated seller. Match the spend to how long the car has left in it.