I bought this 06 GT beauty for 12k with 25700 miles last Oct ....since then I've added CAI from Ford racing ...Ford racing exhaust....Ford racing intake and cams....went from 259 rwhp to 322 rwhp....changed rotors and pads and some suspension parts and Contenintal tires made a huge diff over the Hankook tires that was on the car. Im sure it was motorcraft 5w 20 in it when I bought it.....switching to Penzoil Synthetic made noticeable difference in the engine sound at idle....now smooth and I changed out the transmission oil too but used Ford motorcraft. For a little over 16k i have a car that comes close to a new 30+k Mustang in performance.