Is it necessary for a 700R4 converter to lock up?

Yes, a lock-up torque converter is beneficial for a 700R4 transmission as it improves fuel efficiency and reduces engine RPM at highway speeds. Locking the converter eliminates slip between the engine and transmission, resulting in better power transfer. However, while it is not strictly necessary for the converter to lock up for the transmission to function, not having a lock-up feature can lead to decreased performance and increased fuel consumption.