svt, I even checked the Hanes manual and it says "drop transmission pan, replace filter, add appropriate fluid. Your 4.6L Mustang holds 12.1 quarts of Mercon V." If that's what they went by it could be too much fluid. However, for humors sake, my last car had instructions that read something like this -
1. Make sure car is cold.
2. Warm car up
3. Drive car around town for a while to ensure it is warm.
4. Park for a while.
5. Turn the car off to cool down
6. Drive around town some more to warm transmission fluid up. (But not too much)
7. Park somewhere and shift into 1st gear
8. Rev engine gently.
9, Shift into 2nd gear
10 Rev engine gently
11. Order a pizza
12. Shift into neutral
13 pour Parmesan Cheese on Pizza
14. Drive around town some more until engine is warm again
15. Park somewhere to let engine cool off.
16. Eat another slice of pizza
17. Get out and check the dipstick
18. If level on dipstick is below the Add Fluid line, Add 1/4 of a quart, replace dipstick
19 Repeat steps 1-18 until fluid has reached a desirable level.
So has he checked the fluid yet?