I bought a 20 oz. bottle of "lucas oil automatic transmission fluid conditioner" for my 93 ford taurus 3.8L V6 automatic GL. It has 145,000 miles on it. I want to add a 20 oz. bottle of this lucas oil transmission fluid conditioner but don't know if I should remove some of my AT fluid before I add it or just pour in the bottle to my existing AT fluid. The directions are not clear to me.