Compatible, OEM or genuine: what the word on a quotation actually commits you to
A quotation that says "replacement" is telling you something specific about who made the part and what backs it. If the word is vague, the part usually is too.
Three words, three different claims
They are not marketing adjectives. Each one answers two questions: who manufactured the part, and who will stand behind it if it fails. The price difference between them is usually the second answer.
- Genuine — manufactured and packaged by the machine brand, sold with that brand’s warranty and traceability.
- OEM — manufactured by the original equipment maker, but often sold without the brand’s box or warranty.
- Compatible (also "aftermarket" or "replacement") — made by a third party to fit the same machine; quality depends entirely on which third party.
Why "OEM" appears on things that are not OEM
The word is widely used on trading listings to mean "fits like the original". Treat it as unverified until the seller names the factory that made the part. A seller who cannot name the manufacturer is selling a compatible part with a better-sounding label, and a quotation that repeats that label passes the problem to you.
Where a copied dimension stops being enough
Housings, threads and shaft diameters are easy to copy, so a compatible part usually fits. The difference hides in what you cannot photograph:
- Filter elements — separation efficiency and pressure drop depend on the media, its area and how it is pleated; a cheap separator can fit perfectly and still let oil carry over.
- Bearings — steel grade, heat treatment and clearance class decide life, not the bore and outside diameter.
- Seals — compound hardness and lip geometry decide whether it weeps at temperature, and a drawing shows neither.
What a quotation should print, whoever the seller is
Ask for these four lines in writing. A seller who quotes compatible parts seriously will already have them:
- The exact word: genuine, OEM or compatible — not "original quality" or "same as original".
- The interchange or cross-reference number the part is matched to.
- Which attributes were matched — dimensions only, or material and performance too.
- What is not confirmed, in plain words, so you know what you are accepting.
How this is handled here
When a factory we work with makes a part to fit another brand’s machine, we write compatible in the quotation and name the interchange number. When a factory sells genuine parts, the quotation says genuine and the price reflects it. What we do not do is call a compatible part genuine because it arrived in a convincing box — that claim would be yours to defend, not ours.
The fastest way to lose a maintenance customer is a compatible part sold as genuine. The second fastest is a genuine part sold without saying so, at a price that let the buyer assume aftermarket.