Guides

OEM vs Aftermarket Parts: How to Explain It to Customers

OEM, OES, aftermarket, remanufactured, rebuilt and used parts in plain words, what the FTC says about warranties, the disclosure rules in California, New York and Washington, and the talk track that lets the customer choose.

Ijharul Islam October 21, 2026 10 min read

OEM vs aftermarket parts is a question your service advisors answer every day, usually with a customer who has read one forum post and is worried about the warranty. The answer they give decides whether the customer trusts the price, picks the option that suits the car, and comes back when the part wears out.

More on this topic: Running an auto repair shop, every guide in one place.

This guide gives your counter the definitions in plain words, what the FTC actually says about warranties, what California, New York and Washington make you write on the estimate and invoice, and word-for-word scripts. For the wider skill of explaining a repair, see our guide on how to explain repairs to customers.

The short answer

OEM vs aftermarket parts, in short: OEM parts are made for or by the automaker; aftermarket parts come from other companies at many quality levels. The FTC says using aftermarket or recycled parts doesn't by itself void a warranty. Offer priced options and label each part's type on the estimate and invoice, as California, New York and Washington require.

Key takeaways

OEM means made for or by the vehicle manufacturer; aftermarket means made by someone else. Remanufactured, rebuilt and used parts are separate categories with their own labels.
The FTC's consumer page says: "Your warranty stays in effect if you use aftermarket or recycled parts." The manufacturer or dealer must prove the part caused the damage before denying coverage.
The FTC's used-parts guides require used, rebuilt and remanufactured parts to be disclosed; California, New York and Washington add specific OEM and aftermarket body-part labels.
Present parts as good, better and best lines on the estimate, with the brand and warranty for each, and let the customer pick.
Write the choice down: the part type and brand on the estimate, the approval, and the same label on the invoice.

Disclosure: we make BayRobin, an AI receptionist and front office for independent repair shops, and show where it fits. Everything here works without it. Figures from other companies come from their public pages, checked in October 2026 and linked at the end.

What is the difference between OEM, OES, aftermarket, remanufactured and used parts?

The difference is who made the part and whether it's new. Use the same words every time so the customer hears a consistent story:

Part type	What it is	How to label it
OEM	Made for or by the vehicle manufacturer and sold through its dealer network. California's rules define an OEM crash part as one "made for or by the original vehicle manufacturer".	"New, OEM" plus the part number
OES	Short for original equipment supplier: a company that makes parts for the automaker, selling the same or a similar part in its own box. No rule we read defines it.	"New" plus the brand and part number; in California, a crash part not made for or by the automaker is non-OEM
Aftermarket	New, made by another company. Washington defines an aftermarket body part as one made "by someone other than the original equipment manufacturer" and sold outside the automaker's normal channels.	"New, aftermarket" plus the brand and part number
Remanufactured	In Washington's words, a used assembly taken apart "with the core parts being remachined and all other parts replaced with new parts".	"Remanufactured"
Rebuilt	A used assembly "dismantled and inspected with only the defective parts being replaced" (Washington's definition).	"Rebuilt"
Used or recycled	Taken from another vehicle, usually through a recycler.	"Used"

Quality runs across these lines, not between them: aftermarket ranges from budget to premium, and a remanufactured alternator with a good warranty can be a sensible choice on an older car. That's why the brand and the warranty belong on the estimate, not just the category.

Does using aftermarket parts void a car's warranty?

No, not by itself. The FTC's consumer page on auto warranties, dated April 2024, says it plainly:

"Your warranty stays in effect if you use aftermarket or recycled parts." ... "The manufacturer or dealer must prove the aftermarket or recycled part caused the damage before they can deny warranty coverage." (FTC, Auto Warranties and Auto Service Contracts)

The rule behind it is the Magnuson-Moss Warranty Act. The FTC's regulation, 16 CFR 700.10(c), says "No warrantor may condition the continued validity of a warranty on the use of only authorized repair service and/or authorized replacement parts" for non-warranty work, unless the part or service is provided free or the FTC grants a waiver.

Two limits are worth telling customers. If a defective part or a bad installation damages a covered part, the manufacturer can deny coverage for that damage. And if the warranty covers a repair for free, the FTC says the company "can make you use repair facilities it chooses": send that customer to the dealer for the covered repair. The FTC also tells drivers to keep maintenance records, which is one more reason your invoice should show the date, mileage, part brand and part number.

How should a service advisor explain OEM vs aftermarket to a customer?

Lead with what the customer cares about (fit, life, warranty, price) and keep the brand debate out of it. A talk track that works at the counter or on the phone:

The standard explanation

"For your front brakes I can quote it two ways. The factory part is the same one the car came with, about $X, with a [term] warranty. The aftermarket part is made by [brand], which we use every week, about $Y, with a [term] warranty. Both fit and both are new. The difference is price and how long they're expected to last. Which would you like?"

When the customer asks if aftermarket will void the warranty

"No. The FTC's guidance is that using an aftermarket part doesn't void your warranty, and the manufacturer would have to show the part caused a problem before denying a claim. If a repair is covered free under your warranty, though, the dealer is the place to have it done, and I'm happy to tell you that."

When the customer says aftermarket is junk

"Some is, which is why we don't use it. We stick to a few brands we've seen hold up, and we stand behind the job with our own warranty. If you'd rather have the factory part, that's a good choice too, and here's the price."

Swap the placeholders for your real brands, prices and warranty terms, and never claim a part is "OEM quality" unless you can say what that means for that part. If the car has an open recall for the component, mention it first: under 49 U.S.C. 30120 the automaker remedies a recall defect without charge, except on vehicles first sold more than 15 years before the notice. Our guide to checking open recalls covers the lookup.

What do the rules say you must disclose about parts?

Federal guidance covers used parts everywhere; several states add labels for OEM and aftermarket body parts. The rules we read:

Rule	What it requires
FTC, 16 CFR 20.1 (all states)	Don't present a used, rebuilt or remanufactured part as new; disclose it clearly in ads, invoices and packaging
California BAR and BPC 9884.8	Estimate parts are new unless identified as used, rebuilt or reconditioned; new crash parts are OEM unless identified as non-OEM aftermarket or used; "Opt-OEM", "Alt-OEM", "Like Kind Quality" and "Quality Replacement Part" don't satisfy the rule; the invoice states each part's status
New York, 15 NYCRR 82.5	Estimate marks any part that isn't new "of at least original equipment quality"; body parts marked new OEM, new aftermarket or used on the estimate and invoice
Washington, RCW 46.71.015	Invoice shows whether parts are rebuilt or used and, for collision repair, aftermarket or non-OEM body parts

Other states have their own versions; our auto repair invoice template covers the invoice side, and our New York repair shop laws guide goes deeper on Part 82. This isn't legal advice: statutes and regulations change, and cities and counties can add rules of their own, so check the current official text or ask a lawyer or your state association before you change your forms.

How do you write good, better, best parts options on an estimate?

Put each option on its own priced line with the brand, part type and warranty, so the customer approves one and declines the rest. A worked example for front brake pads and rotors, with assumed prices:

Option	Parts	Parts price	Labor (1.5 h at an assumed $140)	Total before tax	Parts warranty
Good	New, aftermarket, economy pads and rotors, [brand] [part nos.]	$140.00	$210.00	$350.00	12 months
Better	New, aftermarket, premium ceramic pads and coated rotors, [brand] [part nos.]	$210.00	$210.00	$420.00	24 months
Best	New, OEM pads and rotors, [part nos.]	$330.00	$210.00	$540.00	Automaker parts warranty

The figures are illustrations; price from your own costs and parts markup matrix (the free parts markup calculator prices any part cost through your tiers and shows the margin). A few habits keep the choice clean:

Recommend one option and say why ("for how you drive, I'd do Better"), rather than reading three prices.
Keep labor the same on every line unless the job really differs, so the comparison is about the part.
Record which option the customer approved, with the date, time and how they approved it.
Carry the same label to the invoice: "New, aftermarket, [brand] [part no.]".
Match your shop warranty to the part; our warranty policy guide covers parts-dependent terms.

More on laying out lines in how to write an auto repair estimate.

When should you recommend OEM parts?

Recommend OEM when the automaker's procedure, the customer's coverage or your own comeback history points to it. Common cases:

Collision and structural work. Automakers publish position statements on parts and procedures; OEM1Stop links to them. Insurers and leases may also set rules, so ask.
Repairs covered free under a warranty or recall. Send those to the dealer; it costs the customer nothing.
Parts tied to calibration or programming. Follow the automaker's repair information for that vehicle.
Parts with a history of comebacks in your shop. Your warranty records are the best guide to where aftermarket hasn't held up.

Everywhere else, a good aftermarket part from a brand you trust is a fair offer, as long as the customer knows what they're getting.

Frequently asked questions

Are aftermarket parts as good as OEM?

Some are better, some worse; quality varies by brand more than by category. Choose a few aftermarket brands with a record in your shop and a warranty you can stand behind, and offer OEM as an option.

Does using aftermarket parts void my warranty?

Not by itself. The FTC says your warranty stays in effect if you use aftermarket or recycled parts, and the manufacturer or dealer must prove the part caused the damage before denying coverage.

What does OES mean on a car part?

Original equipment supplier: a company that makes parts for the automaker and sells them in its own box. No federal or state rule we read defines it, so label the part with its brand and part number.

Does a shop have to tell you if a part is used or rebuilt?

Yes. The FTC's guides at 16 CFR 20.1 require used, rebuilt and remanufactured parts to be disclosed clearly, including on invoices, and California, New York and Washington have their own invoice labeling rules.

Why are OEM parts more expensive?

They usually come through the automaker's dealer network with its pricing and packaging. Show both prices side by side and let the customer decide what the difference is worth.

Where BayRobin fits

In BayRobin, repair orders are built from canned jobs with labor at your rate and parts and fees from your price book, and the customer approves or declines each service on one link, so good, better and best can go out as separate lines and the choice is recorded; see inspections, estimates and invoices. BayRobin doesn't order parts or carry parts catalogs: you set the part, brand and price on each line. BayRobin is free until your first 10 booked jobs, no card up front. Start free or see pricing.

Sources

Competitor details in this post were checked against these public pages in October 2026. Products and prices change, so confirm with each vendor before you decide.

#parts #service writers #estimates #state law