Toyota Genuine Type T-IV fluid has been specifically engineered and tested to meet the requirements of Toyota automatic transmissions. It provides the optimal friction characteristics, temperature stability, and wear protection for these transmissions. Using a fluid that does not meet Toyota's specifications could result in issues such as poor shifting, increased wear and tear on transmission components, and even transmission failure.
If you are unsure about which transmission fluid to use in your Toyota vehicle, it is best to consult your vehicle's owner's manual or a qualified automotive technician. Using the correct fluid will help to ensure the continued smooth operation and reliability of your transmission.