Age or mileage, whichever comes first
The belt runs inside the engine in oil, so it ages on the calendar as well as on the clock. A Fiesta that only does short trips into town can reach the eight-year age limit with barely 30,000 miles on it, and its belt is just as worn as one on a car that has done 80,000.
- Short, cold trips age the belt faster than the mileage suggests.
- Stop-start driving fills the oil with moisture and fuel, which attacks the rubber.
- A used car with no record of a belt change should be treated as overdue.
Working out when yours is due
Take the year your Ford was first registered and add the years in the interval. A 2017 Focus 1.0 EcoBoost reached its eight-year limit in 2025, whatever the mileage. A 2019 Transit Custom 2.0 EcoBlue doing 30,000 miles a year reaches 144,000 miles in under five years, long before its ten-year limit.
What happens if you go past it
Once a wet belt is past its best it starts shedding rubber into the oil. The debris blocks the oil pickup, oil pressure falls and the engine can be damaged beyond repair. A replacement engine typically costs £3,000 to £5,000, against a fixed-price belt change done on time.