I have a 2013 Tacoma with a 4 speed Automatic trans and has 116k miles on the ODO, ive always done and pan drain and refill every 30k miles but never a full flush out. ive ordered 12 quarts of genuine Toyota t-IV fluid should I just continue on with 4 quart pan drains at 30k and spread out those 12 quarts or is it time to get it all out with a full flush. the trucks a daily driver no towing and the ATF visually looks very good. it takes exactly 4 quarts to pan drain the whole system takes 11 quarts.