Question: On several occasions you have covered various types of motor oils, but how about transmission fluids? Recently, I purchased a Lincoln Town Car with automatic overdrive transmission. Ford calls for it to use Dexron II fluid, Series D, and gives a Ford part number. For years, I have been using Dexron II M2C33-F Type fluid in Fords. Can you help with some information on the proper type of transmission fluids?--A.E.S.
Answer: Motor oils are a relatively simple issue compared to transmission fluids. Ford alone has three different fluids that it specifies for various model years of its cars.
How important is the right fluid? It's critical to the longevity and proper function of an automatic transmission, according to Norm Hudecki, a Valvoline oil expert. Some automatic transmissions require what is called friction-modified fluids; others require non-friction-modified fluids.
Used correctly, the friction-modified fluids provide smoother, quicker shifting. They contain sulfur-phosphorous modifiers that allow clutches to slide rather than grab. But they should be used only where specified by the manufacturer. One type of friction-modified fluid is Mercon, which is recommended by Ford for only some of its cars.