What to Know Before You Order
Buying car parts online means you need your vehicle's exact year, make, model, and engine size before you search — not just "a Honda" or "a Ford truck." Parts that fit a 2019 Honda Civic do not fit a 2020 model, and a part for the 1.5-liter engine will not work in the 2.0-liter version. Most online retailers will not accept returns on parts that were ordered for the wrong vehicle, so ordering incorrectly costs you money and time.
The second thing to understand is that you are buying from a retailer, not from the manufacturer. That retailer sources parts from various suppliers — some original equipment manufacturer (OEM) parts made by the company that built your car, and some aftermarket parts made by third parties. OEM parts cost more but carry a may provide they will fit. Aftermarket parts cost less but vary in quality depending on the brand. Neither is inherently better; it depends on what you are replacing and how long you want it to last.
Return policies vary widely. Some retailers accept returns within 30 days if the part is unused and in original packaging. Others do not accept returns on parts at all. Read the return policy before you complete your purchase, not after the part arrives and does not fit.
Key Takeaways
- You must have your vehicle's year, make, model, and engine size before you search, because parts are not interchangeable across model years or engine types.
- OEM parts are made by your car's manufacturer and cost more; aftermarket parts are made by third parties and cost less but vary in quality.
- Most online retailers will not accept returns on parts ordered for the wrong vehicle, so verify fitment before you buy.
- Check the retailer's return policy before you order, because some do not accept returns on parts at all.
- Shipping times and costs vary by retailer and part type, so compare total price including shipping, not just the part price.
Finding Your Vehicle Information
Your vehicle identification number (VIN) is the fastest way to order the right part. This 17-character code is printed on your vehicle registration, insurance card, and the dashboard on the driver's side where it meets the windshield. You can also find it on the door jamb on the driver's side. Most online retailers have a search box where you can enter your VIN, and the system will automatically show you parts that fit your specific vehicle.
If you do not have your VIN handy, you can enter your year, make, model, and engine size instead. The engine size is usually listed on a sticker under the hood or in your owner's manual. If you are unsure, call your car's dealership with your license plate number and they will tell you the engine size over the phone.
Some retailers also let you upload a photo of your current part, and their system will match it to the correct replacement. This works well for common parts like air filters or batteries, but less reliably for larger or more complex components.
Comparing Retailers and Prices
The major online retailers for car parts include RockAuto, AutoZone, O'Reilly Auto Parts, NAPA, Amazon, and eBay. Each has different pricing, shipping costs, and return policies. RockAuto typically has the lowest prices but slower shipping. AutoZone and O'Reilly offer same-day or next-day pickup at physical locations if you need the part urgently. NAPA and dealership websites carry more OEM parts. Amazon and eBay have a wider range of sellers, which means prices vary more and you need to check seller ratings.
When you compare prices, add the shipping cost to the part price. A part that costs $40 with $25 shipping is more expensive than a part that costs $55 with free shipping. Some retailers offer free shipping above a certain order amount, so if you are buying multiple parts, that threshold might matter. Check whether the retailer charges a restocking fee if you return the part — some do, and some do not.
Read the product description carefully. It should state what vehicle the part fits, what condition it is in (new, refurbished, or used), and whether it comes with a warranty. If the description does not say, contact the seller before you order.
Understanding Part Condition and Warranties
New parts are manufactured and have never been installed. They come with the longest warranty, usually one to three years depending on the part type. Refurbished parts have been used, removed, cleaned, tested, and restored to working condition. They cost less than new but usually come with a shorter warranty, often 30 to 90 days. Used parts are removed from salvage vehicles and sold as-is, usually with no warranty at all.
For safety-critical parts like brakes, steering components, or suspension parts, buy new or refurbished from a reputable seller. For wear items like air filters, cabin air filters, or wiper blades, used parts are usually not worth the risk. For engine or transmission parts, new is safest unless you are buying from a salvage yard you trust.
Check what the warranty covers. Some warranties cover defects in materials or workmanship but not installation labor. Others cover the part only if it fails within a certain number of miles or months. If the warranty is unclear, email the seller and ask for clarification before you order.
Checking Seller Ratings and Reviews
On Amazon and eBay, look at the seller's overall rating and read recent reviews from people who bought the same part. A seller with 98% positive feedback is generally trustworthy. A seller with 85% positive feedback or lower, or one with many recent negative reviews about wrong items or defective parts, is a risk. Do not assume a low price is a bargain if the seller has poor ratings.
On dedicated auto parts sites like RockAuto or AutoZone, the retailer itself is the seller, so you are not comparing individual sellers. Instead, read customer reviews of the specific part you are buying. If a part has dozens of reviews and an average rating below 3 out of 5 stars, that is a signal that it may not fit correctly or may fail quickly.
If you are buying from a dealership website, the dealership is the seller and you are buying OEM parts directly from the manufacturer's authorized distributor. These are the most expensive option but carry the strongest may provide of fitment.
Placing Your Order and Tracking Delivery
Before you click "buy," verify one more time that the part description matches your vehicle. Check the year, make, model, and engine size. If the listing says "fits 2015–2019 Honda Civic," make sure your Civic falls in that range. If you are unsure, contact the seller and ask.
Save your order confirmation email. It contains your order number, tracking information, and the seller's return address if you need to send the part back. Most retailers send a shipping notification within one to three business days with a tracking number. Use that number to monitor when the part will arrive.
When the part arrives, open the package when ready and inspect it. Check that it matches the description — the right part number, the right color, the right size. If it is damaged, take photos before you touch it. If it is the wrong part, contact the seller within the return window (usually 30 days) and explain the problem. Most retailers will issue a return label and refund your money once they receive the part back, though some deduct a restocking fee.
When to Buy Online Versus In-Store
Buy online when you know exactly what part you need and you have time to wait for shipping. Online prices are usually lower, and you can compare multiple retailers without leaving home. Buy in-store when you need the part today, when you are unsure which part you need and want to talk to a technician, or when you want to return the part when ready if it does not fit.
Many retailers now offer both options. You can order online and pick up at a local store within a few hours, which combines the price advantage of online shopping with the speed of in-store pickup. AutoZone and O'Reilly Auto Parts both offer this service. If you are in a hurry, this is often the best choice.
If you are having the part installed by a mechanic, ask the mechanic which retailer they prefer and whether they can order it for you. Some mechanics have accounts with specific suppliers and can get parts at a discount. Others will install a part you bring them, though some charge a small fee for that service.
Frequently Asked Questions
What if the part I ordered does not fit when it arrives?
Contact the retailer or seller within the return window (usually 30 days) and explain that the part does not fit your vehicle. Most will issue a return label and refund your money once they receive the part back. Some charge a restocking fee of 10–20%. A few do not accept returns on parts at all, so check the return policy before you order.
Is it safe to buy used parts online?
Used parts are cheaper but come with more risk. They have no warranty in most cases, and you cannot inspect them before you buy. Used parts work well for non-critical items like trim pieces or mirrors. For engine, transmission, or brake parts, buy new or refurbished from a seller with strong ratings.
How do I know if a part is OEM or aftermarket?
The product description will say "OEM" or "original equipment manufacturer" if it is made by your car's manufacturer. If it does not say OEM, it is aftermarket. Dealership websites sell only OEM parts. Other retailers sell both, and the listing will specify which type you are buying.
Can I return a part if I ordered it for the wrong vehicle?
Most retailers do not accept returns on parts ordered for the wrong vehicle, because they cannot resell it. Some will accept a return if you contact them before the part ships, so if you realize you made a mistake, reach out when ready. After the part arrives, your options are limited.
What shipping method should I choose?
Standard shipping usually takes 5–10 business days and costs the least. Expedited shipping takes 2–3 business days and costs more. If you need the part urgently, order in-store pickup instead of paying for expedited shipping, because pickup is usually faster and cheaper.