When you bring your vehicle in for repair, one of the first decisions is what parts to use. OEM parts come from the original manufacturer. Aftermarket parts come from independent manufacturers. The right choice depends on the part, the vehicle, your budget, and how long you plan to keep the car. Here is an honest comparison.
What OEM Actually Means
OEM stands for Original Equipment Manufacturer. An OEM part is identical to the part installed at the factory when the vehicle was new, sourced from the same supplier or the manufacturer's own production. OEM parts come in factory packaging with factory part numbers.
OEM does not mean dealer-only. Many OEM parts are available through parts suppliers at lower prices than dealer counters charge. We source OEM parts through our wholesale accounts at savings versus dealer pricing.
What Aftermarket Means
Aftermarket parts are made by manufacturers other than the original vehicle manufacturer. Quality varies enormously. Premium aftermarket brands (Bosch, Denso, NGK, Bilstein, Monroe, Brembo, Akebono, Aisin) make parts to OEM specifications and often supply the factory directly under different branding. Mid-tier brands meet basic specifications and offer significant cost savings. Low-tier brands cut corners and fail prematurely.
We use premium aftermarket brands where they are appropriate. We do not use bottom-tier aftermarket. The savings are not worth the comebacks and warranty claims.
When OEM Makes Sense
Sensors and electronics. OEM sensors are calibrated for your exact vehicle and rarely cause check engine lights or fitment issues. Aftermarket sensors, especially cheap mass airflow sensors and oxygen sensors, fail at higher rates and trigger codes that look like other problems.
Body panels and exterior parts. Fit is critical on body panels. OEM panels match factory paint codes and gaps. Aftermarket body parts often need adjustment to fit and may not last as long.
European luxury vehicles in general. The parts ecosystem for BMW, Audi, Mercedes, and MINI is dominated by OEM and premium aftermarket. Cheap aftermarket parts on European cars fail at high rates and often cost more in labor over time than the cost savings.
Hybrid and EV-specific components. Battery management modules, high-voltage cables, and inverter components should always be OEM. Safety and reliability concerns outweigh any cost savings.
When Premium Aftermarket Makes Sense
Brake pads and rotors. Premium aftermarket brands like Akebono, Brembo, Centric, and Wagner offer pads and rotors that meet or exceed OEM performance, often at lower cost. We use these on most vehicles.
Filters. Premium aftermarket filters (Wix, K&N, Fram Ultra, Bosch) meet OEM specs at lower cost. Air, oil, fuel, and cabin filters from premium brands are excellent value.
Suspension. KYB, Bilstein, Monroe, and similar premium aftermarket brands make struts and shocks that match or exceed OEM. Many performance applications actually use these brands as OEM equipment.
Belts and hoses. Gates, Continental, and Dayco supply both OEM and aftermarket. The aftermarket pricing is lower than dealer for the same quality.
Spark plugs. NGK, Denso, and Bosch supply most OEM plugs. Buying their aftermarket boxed versions saves significant money for identical product.
When to Avoid Cheap Aftermarket
Generic, no-name brands at significantly lower prices typically use lower-grade materials or skip quality steps. Issues we see frequently include: aftermarket water pumps with impellers that fail in months, cheap brake pads that wear rotors faster, low-tier oxygen sensors that trigger codes, knockoff timing belts that stretch, and bargain ignition coils that fail erratically.
The total cost of a cheap part is the part plus the labor to do the job again when it fails. For most components, the labor exceeds the savings on the cheaper part within one or two years.
Warranty Differences
OEM parts typically have factory warranty (12 to 24 months from purchase). Premium aftermarket parts often have similar warranty, sometimes longer. Cheap aftermarket parts may have warranty but the manufacturer is often hard to reach, slow to respond, or out of business.
We back every part we install with our 2-Year/24,000-Mile warranty on parts and labor, regardless of whether you choose OEM or premium aftermarket. If a part fails within that period, we replace it at no charge.
How We Recommend Parts
For each repair, we recommend the part level that gives you the best total value for how you use the vehicle. A daily-driven Honda Accord with 150,000 miles that you plan to keep for two more years gets a different recommendation than a leased BMW under warranty.
We always tell you what we are quoting, OEM or aftermarket, and you can choose. If you want OEM and we initially quoted aftermarket, we update the quote. If you want to save by going aftermarket and we recommend OEM, we explain why before changing the quote.
Why Choose Perry's for Quality Parts Work
Perry's Quality Auto in Simi Valley has built relationships with both OEM and premium aftermarket suppliers since 1997. We have wholesale accounts that give us OEM parts at competitive pricing. We never install bottom-tier parts because we honor our 2-Year/24,000-Mile warranty.
Our ASE Certified technicians and AAA Approved shop is at 2180 First Street, Suite C-10 in Simi Valley. Call (805) 522-5769 for any quote.
Frequently Asked Questions
Are OEM parts always better than aftermarket?
No. Premium aftermarket brands like Bosch, NGK, KYB, Brembo, and Akebono often match or exceed OEM at lower cost on many parts.
When should I insist on OEM?
Sensors and electronics, body panels, European vehicles in general, and any hybrid or EV-specific components.
Do you warranty aftermarket parts?
Yes. Every part we install carries our 2-Year/24,000-Mile warranty on parts and labor, OEM or premium aftermarket.
Can I save money by buying my own parts?
We do not install customer-supplied parts because we cannot warranty them. Our wholesale pricing is competitive with retail.
How do I know which to choose for my repair?
We recommend the right tier for your vehicle, mileage, and ownership plans, and explain the reasoning before any work begins.
Schedule service at Perry's Quality Auto in Simi Valley
Family-owned since 1997. ASE Certified technicians. 2-Year/24,000-Mile warranty on all repairs. Call (805) 522-5769 or book online below.
2180 First Street, Suite C-10, Simi Valley, CA 93065 · Mon-Fri 8:00 AM - 5:00 PM