Did some maintenance on a friend's '07 Grand Marquis today, and when it came to flushing the power steering, he supplied Motorcraft Mercon V. I use MC Mercon V in my power steering systems, and it works great, but I wasn't too sure of using it in his vehicle, because the manual specifically calls for Mercon in the P/S system and specifically states they are not interchangeable. He got 2 cartons of Mercon V to do a transmission flush through the cooler lines (13.2L capacity) and reckoned what was leftover could be used for the P/S, because Mercon is getting very hard to find. As a result we put the P/S flush aside, until I can get a confirmation on something. Dexron III would be a possible alternative, but before going out any spending more money, Motorcraft Mercon V sold in the Middle East is clearly labelled to meet Dexron III specifications: My P/S calls for Dexron III and I use Mercon V instead, never had any issues. But I cannot comment on it's use in a Ford P/S system. Do you all reckon it would it be alright to go with his original plan and use Mercon V in his P/S, seeing this fluid meets Mercon spec? Thanks!