Some people with 2011-2012 Mustangs are having problems shifting their 6-speed transmission while cold now have Ford’s attention as they have released a TSB to take care of the issue. The solution is as simple as replacing the transmission fluid with Motorcraft Dual Clutch Transmission Fluid. You can download the PDF of the TSB-11-03-18.
Some 2011-2012 Mustang vehicles equipped with a MT82 6-speed manual transmission may exhibit increased shift efforts in cold ambient temperatures. This is usually most noticeable in 1st and 2nd gears but may also be noticed in 3rd through 6th gears. The increased shift effort may be the result of the increased viscosity of the transmission fluid in cold weather.
Follow the Service Procedure to correct the condition.
Replace the Motorcraft Full Synthetic Manual Transmission Fluid with 2.6L (2.7 qt) of Motorcraft Dual Clutch Transmission Fluid. Refer to Workshop Manual, Section 308-03A for the transmission fluid draining and filling procedure. This fluid is suitable for use in all ambient temperatures and seasons, and the Scheduled Maintenance guidelines in the Owner Guide can continue to be followed. The use of friction modifiers or other fluid additives is not recommended since although they may provide some immediate improvement in cold shift effort, they are likely to result in long term degradation of the synchronizers.
Eligible Under Provisions Of New Vehicle Limited