normal oil flushes (e.g. WYNNES engine flush) is basically diesal, with a few other bits thrown in.
Auto Transmission fluid is full of cleaners and degreasers, this washes the engine internally and holds on to the junk, for you to emtpy out when you change the oil. You need approx 500ml in with your normal oil, run for approx 200 easy miles, and change your oil.
Many people say it works wonders on noisy tappets!!