How often should the transmission fluid be changed in a Ford Focus?

I just bought a used Ford Focus and I'm not sure when the previous owner last changed the transmission fluid. Is it necessary to change it on a regular basis? If so, how often should it be done?

It is recommended to change the transmission fluid in a Ford Focus every 50,000 miles or every 4 years, whichever comes first.

If you notice any signs of transmission problems, such as slipping or hard shifting, it's best to have the fluid changed immediately.

If you frequently drive in stop-and-go traffic or tow heavy loads, it's a good idea to change the transmission fluid more frequently, around every 30,000 miles.

Not changing the transmission fluid regularly can lead to costly transmission problems down the road. It's better to be safe than sorry.