The most direct route depends on whether you know the exact part number
If you have your car's year, make, and model — or better yet, the part number from your owner's manual or a mechanic — you can walk into an auto parts store, call them, or search their website and find what you need in minutes. If you do not have that information, you will need to either look it up yourself or ask someone who knows your car.
The difference matters because a generic search like "brake pads" will return hundreds of results, and the wrong ones will not fit. Spending five minutes finding your vehicle's exact specifications saves you a trip back to the store or a wasted online order.
Key Takeaways
- National chains like AutoZone, O'Reilly, Advance Auto Parts, and NAPA carry most common parts and can tell you what fits your specific car if you provide the year, make, and model.
- Your car's owner's manual, the sticker inside the driver's door jamb, or your vehicle registration all contain the year, make, model, and engine size you need to identify the right part.
- Online retailers like Amazon and RockAuto often have lower prices than brick-and-mortar stores, but shipping times vary and some parts cannot be returned as easily.
- A mechanic or dealership can order parts for you, which costs more but guarantees the part fits and often includes installation.
- Used parts from junkyards and salvage yards cost less but come with no warranty and require you to inspect them before purchase.
National auto parts chains and what they stock
AutoZone, O'Reilly Auto Parts, Advance Auto Parts, and NAPA are the largest chains in the United States. All four carry brake pads, filters, batteries, belts, hoses, spark plugs, fuses, and other wear items that most car owners replace themselves. They also stock body panels, lights, mirrors, and trim pieces for common vehicles.
Each store has a parts counter where you can describe your car and the problem you are trying to fix, and the staff will look up what fits. You can also search their websites or call ahead. Many locations offer same-day pickup if you order online, and most accept returns within a set window — usually 30 to 90 days — if the part is unused and in its original packaging.
Prices vary between chains and between locations, so if you are buying an expensive part, calling two or three stores takes ten minutes and can save you money. Some stores offer discounts for cash payment or for members of loyalty programs.
How to find your vehicle's specifications
Your car's year, make, model, and engine size are printed on a sticker inside the driver's door jamb — open the door and look at the frame itself, not the door. The same information appears on your vehicle registration and insurance card. If you have your owner's manual, it is there too.
Engine size matters because a 2015 Honda Civic with a 1.8-liter engine needs different parts than a 2015 Civic with a 2.0-liter engine. The door jamb sticker will tell you which one you have. If you cannot find it, you can also search your vehicle identification number (VIN) — a 17-character code printed on your registration — on the manufacturer's website or on free VIN decoder sites.
Once you have this information, you can search any parts retailer's website or call their counter and get an exact match in seconds. This step takes two minutes and prevents you from buying the wrong part.
Online retailers and when to use them
Amazon, RockAuto, eBay, and Walmart all sell car parts, often at prices lower than brick-and-mortar stores. RockAuto in particular is known for discounted prices on filters, batteries, and wear items. The trade-off is shipping time — most orders take three to seven business days, and some parts take longer.
Online shopping makes sense when you know exactly what you need and can wait for delivery. It does not make sense if your car is not running and you need the part today. Return policies vary by retailer and by seller (on eBay and Amazon, different sellers have different rules), so read the return terms before you buy.
Counterfeit parts are more common online than in physical stores, particularly on third-party marketplaces. Buying from the retailer's own inventory rather than from a third-party seller reduces this risk. If you are unsure whether a part is genuine, stick with a national chain or the manufacturer's official website.
Dealerships and mechanics as a source
Your car's dealership stocks parts made by the manufacturer and can order anything they do not have in stock. A mechanic's shop usually has relationships with suppliers and can order parts for you as well. Both options cost more than buying the part yourself — dealerships especially — but they may provide the part fits and often include installation in the price.
This route makes sense if you are having the work done at that location anyway, or if the part is complex and you want someone experienced to install it. It does not make sense if you are buying a straightforward part like an air filter that you can install yourself and you want to save money.
Ask for the part number and the price before you agree to have it ordered. Some shops will let you bring your own part if you find it cheaper elsewhere, though they may charge a small fee for installation.
Used and salvage parts from junkyards
Salvage yards and auto recyclers pull parts from vehicles that have been in accidents or are too old to repair. A used alternator, door panel, or engine block costs a fraction of a new one. The catch is that used parts come with no warranty, and you cannot return them if they do not work.
Junkyards vary widely in quality and honesty. Some test their parts before selling them; others do not. Before you buy, ask whether the part has been tested, whether it comes with any may provide, and what the return policy is. If possible, inspect the part in person before you pay.
This option works well for older cars where new parts are expensive or hard to find, or for cosmetic parts like trim and mirrors where failure is unlikely. It is riskier for critical parts like brakes or steering components where a failure could be dangerous.
Specialty retailers for specific vehicle types
If you drive a truck, motorcycle, RV, or imported car, specialty retailers often have better selection and pricing than national chains. Truck-specific stores carry suspension parts, bed liners, and accessories designed for trucks. Motorcycle shops stock parts for bikes. Import specialists focus on Japanese, German, or European vehicles.
These shops often have staff who know the vehicles deeply and can answer technical questions. They may also offer installation or modification services. Finding them usually means a web search for your vehicle type plus your city, or asking at a local mechanic shop that specializes in your kind of car.
Frequently Asked Questions
What if I do not know what part I need?
Describe the problem to a parts counter staff member or a mechanic — for example, "my car is making a grinding noise when I brake" or "the check engine light is on." They can narrow down what might be wrong and tell you what parts to check or replace. If you are unsure, a mechanic can diagnose the problem for a fee, usually $50 to $150.
Can I return a part if it does not fit?
Most national chains accept returns within 30 to 90 days if the part is unused and in its original packaging. Online retailers have varying policies — check before you buy. Used parts from junkyards typically cannot be returned, so ask about their may provide before you purchase.
Is it cheaper to buy parts online or in a store?
Online retailers like RockAuto are usually cheaper, but you pay for shipping and wait for delivery. National chains are more expensive but you get the part when ready and can return it easily. For expensive parts, call a few stores and compare prices before deciding.
How do I know if a part is genuine?
Buy from the manufacturer's official website, from the car's dealership, or from established retailers like AutoZone and NAPA. On third-party marketplaces like eBay and Amazon, check the seller's rating and read reviews. If the price seems too low, it probably is.
What if my car is old and the part is no longer made?
A salvage yard or auto recycler can often find used parts from the same year and model. Online forums for your vehicle type may also have members selling used parts. A mechanic who specializes in older cars can sometimes suggest a newer part that fits with minor modification.