Which transmission oil has the same specs as 4HP 20?

The transmission oil that has the same specifications as the 4HP 20 is typically a synthetic ATF (automatic Transmission Fluid) that meets the requirements of Dexron III or Mercon specifications. It's crucial to consult the vehicle's owner manual or a professional to ensure compatibility, as manufacturers may have specific recommendations for the best performance and protection. Always check for the appropriate viscosity and any specific additives that may be required.