The most common question when buying spare parts is "original or aftermarket?". What really matters, however, is whether the part is made to a quality that meets the vehicle's needs. Material, dimensional accuracy and durability count far more than the word on the label. In this article we clarify the terms and summarise how to recognise a quality part.
Original, OES and aftermarket: what do the terms mean?
- Original part (OE): sold in the vehicle manufacturer's branded packaging through the authorised service channel. It is the same part the vehicle was built with at the factory.
- OES part: a part with the same or equivalent specifications, sold under their own brand by the manufacturers who supply the vehicle maker.
- Aftermarket part: made by independent manufacturers to the dimensions and function of the original part. Quality varies greatly by manufacturer; a good aftermarket part can deliver original performance at a lower cost.
So "aftermarket" does not mean low quality on its own; what matters is the criteria by which the part is made and inspected.
What defines a quality part
1. Material and heat treatment
Parts such as stabilizer links, ball joints and tie rod ends work under constantly changing loads. The quality of the steel used in the body and studs, and correct heat treatment, determine the part's resistance to both breakage and wear. The difference in service life between two parts that look the same usually comes from here.
2. Dimensional tolerances
Mounting holes, thread pitches, tapered seating surfaces and overall length must match the original dimensions. Even a small deviation makes fitting harder and causes the connection to loosen and develop play early.
3. Rubber and boot quality
The boots and mounts that protect the joints must be made from rubber compounds resistant to heat, ozone, oil and cold. Poor rubber soon hardens and cracks; once the boot tears, the joint inside quickly fails as well.
4. Surface coating and corrosion resistance
Salted winter roads are the biggest enemy of metal parts. A good coating prevents rust from making removal impossible and the part from weakening early. Manufacturers measure this resistance with accelerated tests such as the salt spray test.
5. Grease, sealing and fitting hardware
In ball joints, the right grease and good sealing are the key to quiet, long-lasting operation. Quality nuts and fasteners in the box ensure the part is fitted correctly the first time.
What to look for when buying
- Match the OEM number: make sure the part matches the OEM number of the part on your vehicle. This minimises the risk of a wrong part.
- Check the chassis code and side: different body types of the same model may use different parts; front/rear and right/left also matter.
- Look at the packaging and label: the product code, manufacturer details and barcode should be legible; sloppy packaging is a warning sign.
- Ask for an invoice and warranty: an invoiced, guaranteed product gives you assurance and someone to turn to if a problem arises.
- Don't look at price alone: a very cheap part soon means repeat labour and lost time at the vehicle.
The ORTAŞ Autoparts approach
At ORTAŞ Autoparts, we match every part with its OEM numbers and vehicle compatibility list when sourcing, and offer our dealers only products that have passed quality control. We clearly list the makes, models and chassis codes each product fits on our website and in our E-Catalogue, making it easy to find the right part the first time.