Should I Check Transmission Fluid While the Car Is Running?
Checking transmission fluid with the engine running is often the correct procedure for many automatic transmissions, because the fluid must be circulated and at operating temperature to give an accurate dipstick reading. However, it is not the right approach for all vehicles. Manual transmissions, some continuously variable transmissions, and sealed transmissions often require checking with the engine off or from underneath the vehicle. Always follow the procedure in your owner’s manual and prioritize safety when working near a hot, running engine.