1 pointI only put on 5000 miles a year, so I change it every 15,000 miles. When the car is out of its extended Ford warrantee, I'll probably do it every 10,000 miles. At this point, if it blows, I'm still under warranty so every 15,000 miles is what I decided to do. I have the dealer do it. If I recall correctly, it's about 100 bucks or so. I did have to convince them over time to do it........ as they gave me the standard "FORD says it's lifetime fluid".
1 pointI changed my annually and many others do the same. It is not difficult to suck the old fluid out and put new in if you are a do-it-yourselfer.....although it can be messy. If you don't want to do it, there are places that will. You might want to check around. It is good maintenance.