OEM vs Aftermarket Parts: Everything You Need to Know
FixMyCar explains the pros and cons of different car parts.
Book a car repair nowEllie Dyer-Brown
Friday August 15 2025
4 min read
When your car’s in the garage, it’s easy to focus on the repair itself and not the parts going under the bonnet. But those parts matter more than you might think.
The choice between OEM parts and aftermarket parts can affect your car’s performance, lifespan, resale value and even warranty. That’s why one of the smartest questions you can ask your mechanic is: What parts will you be using?
In this guide, we break down the pros and cons of both options, so you can make an informed choice.
What does OEM stand for in car parts?
OEM stands for Original Equipment Manufacturer. These parts are built to the exact same specifications as the ones your car originally came with, so you get the same fit, performance and quality.
OEM vs OE - what's the difference?
There are two related terms that are worth knowing:
OE (Original Equipment): Parts made directly by your car’s manufacturer.
OEM (Original Equipment Manufacturer): Parts designed by your manufacturer but produced by a trusted third-party company to the same strict standards.
Either way, OEM parts are essentially identical to the originals your car had when it left the factory.
What is an OEM manufacturer?
An OEM manufacturer is a company that produces components used in another brand’s finished products.
For example, your car maker might design a brake disc but outsource the manufacturing to a specialist engineering company. As long as it’s made to the same design and quality standards, it’s considered OEM.
The pros and cons of OEM car parts
Why choose OEM? You’re getting guaranteed compatibility and quality, but you may pay more and wait longer for delivery.
| Pros | Cons |
|---|---|
| ✅ Guaranteed quality | ❌ Higher cost |
| ✅ Perfect fit for your vehicle | ❌ May have to be ordered in, resulting in delays |
| ✅ Often preferred by potential buyers | ❌ Some OEM-labelled parts are actually rebranded aftermarket parts |
| ✅ Likely to last longer than alternatives | - |
| ✅ May come with warranty | - |
What are aftermarket car parts?
An aftermarket part is any part not sourced from the original manufacturer or their approved OEM supplier. These are made by independent companies as replacements for OEM parts.
Aftermarket parts - also known as alternative parts - are often cheaper and more widely available, but quality can vary significantly.
Are aftermarket car parts good?
The quality of aftermarket parts varies. Some will undoubtedly be very good – but it’s hard to know for certain before you buy, because it’s unlikely they will have gone through the same rigorous testing as an original part.
Many aftermarket parts will last for a fraction of the time an OEM part would, so even though they’re much cheaper to buy, they may need to be replaced more often.
The main benefit of aftermarket parts, aside from their lower price tag, is that they provide a wider range of options, creating the possibility for customisation. If you don’t like your car’s original exhaust, for example, you can change it – as long as you follow the laws around exhaust noise.
The downside to the variety of aftermarket parts is that it can be harder to choose the right part for your vehicle.
Pros and cons
| Pros | Cons |
|---|---|
| ✅ Cheaper than OEM | ❌ Quality is inconsistent between brands |
| ✅ Easier to find in stock | ❌ May invalidate your vehicle’s warranty |
| ✅ Fast delivery | ❌ May not last as long as OEM equivalents |
| ✅ Wider variety | ❌ Could have compatibility issues |
Which parts should I choose - aftermarket or OEM?
Your decision will usually come down to budget vs quality:
Choose OEM if you want the best possible fit, long-term reliability and peace of mind, especially for critical components like brakes, suspension or engine parts.
Choose aftermarket if cost is your main concern, but take time to research reputable brands and check compatibility with your vehicle.
The parts you choose for your car repairs make a real difference to performance, safety and value for money. OEM parts give you factory-level quality but at a higher price, while aftermarket parts offer savings and variety but with a wider range in quality.
If you’re unsure which option is right for your car, ask your mechanic for advice, and always prioritise safety and reliability.
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Ellie is FixMyCar's Content Manager. She has over three years of experience writing about cars and regularly collaborates with automotive experts to provide trustworthy advice for drivers that is easy understand. Her work has been featured in Yahoo! Finance, iNews, The Daily Express and The Sun. She has a BA in English literature and an MA in creative writing from Durham University. Outside of work, Ellie follows F1 and eagerly awaits Ferrari's next era of dominance in the sport. She drives a Suzuki Swift.