What type of transmission fluid do you use in a 1997 mercury mountaineer?
Ford developed a new fluid starting in 1997 called Mercon V. This replaces Mercon on some transmissions but in 1997 only two. The 4R44E & 5R55E. All other transmissions use Mercon. Using the wrong fluid can cause problems. I suggest you look on the dipstick or in your owner’s manual to see which fluid you need. If you cannot find the information there, call your local Ford dealer and be specific about your vehicle. Make sure they understand that Mercon V is only to be used in these 2 transmissions. You may need to crawl under the vehicle and see exactly which transmission you have installed. Do not just take someones word on this. Be sure they know or you may do harm to the transmission.