I see it listed a Mercron 5 fluid which I am told is synthetic. I would still chance it at 30k or at least 60k if you plan on keeping the vehicle long term. Coolant is Motorcraft Premium gold which is long life type.
If you want to keep this vehicle for any length of time the service the trans every 30,000 miles. Let's face it a $150 spent every two years is money well spent. THERE IS NO SUCH THING AS LIETIME COOLANT!!! Spend the $100 or less to have the cooling system serviced. Forget about the extended life coolant. Have it serviced once a year. Any fluids that are in your car need to be changed. Brake fluild, Power steering fluid and even the refigerant in the A/C system.