Wynn’s TranSERVE¨ Automatic Transmission Flush and Fill Machine is a 12V service machine that operates from the vehicle’s battery to simply and effectively flush the transmission oil system of automatic transmission. The machine automatically detects the correct flow direction and has a high fluid exchange rate of up to 90% compared to only 30-35% with a classic drain and fill. The machine achieves this with no mixing of old and new fluid.