How should I handle “oem vs aftermarket where to buy auto parts” when shopping for “where to buy auto parts”?

Choose by failure consequence, evidence, warranty, and labor cost. OEM can simplify specification matching; a documented aftermarket part can be suitable when its application data and quality controls are clear. FTC guidance says aftermarket use alone does not automatically void a vehicle warranty, although damage caused by a defective part or installation may be excluded. Verify the final application and written terms with the part manufacturer, seller, or installer before purchase. UK FAQ.