The Toyota Prius does not have a traditional gearbox with gear oil. It uses a planetary gearset within its hybrid transaxle, which is lubricated by ATF (Automatic Transmission Fluid).
It's important to use the correct ATF for your specific Prius model. Refer to your owner's manual or contact your local Toyota dealership for the recommended ATF type.
Using the wrong fluid can damage your transaxle and void your warranty.