There are varying figures on when to change the ATF (Automatic Transmission Fluid).Ford service manuals do not give any figures for changing the ATF and as such there are figures of 37,500 miles to 150,000 miles. You do not say how many miles your car has done but we would suggest (given that you are intending to keep the car) that we would change the ATF somewhere between 60,000 and 80,000 miles.