Locked Period: With all the clutch engaged, the torque converter transitions from a fluid coupling to a mechanical coupling, removing slippage and improving drivetrain efficiency. Even a minimum level of oil in use, underneath centrifugal power of rotation can start to drive the piston and drag the clutch. Figure 6 https://torqueconverterclutch10741.bloguerosa.com/33221826/the-2-minute-rule-for-torque-converter-clutch