Why are timing belt replacement intervals so different?

Question

I was advised by Volkswagen to have my timing belt replaced at the 5 year / 40,000 miles interval, but my wife who has a Ford Focus was told by Ford it wasn’t needed until at least 10 years / 100,000 miles. The cars in questions were. Looking online, most VWs have 5 year intervals and Fords 10 year intervals. Would my VW have lasted comfortably to the 10 year mark? Why are these so different? I can’t imagine VW use less quality parts than Ford. In fact quite the opposite I could assume.

Thanks

Answer 1

Favorite Answer

Because these intervals are determined by the engineers that designed the engines. If VW says to replace the belt every 5 years or 40,000 miles, then that's what you need to do. Likewise for the Ford. They specify different intervals for a good reason.

Answer 2

Who cares WHY? 

Just follow the manufacturer's recommended schedule! 

Make sure to use an OEM belt from the dealership. 

If you want to buy an inexpensive (cheap) Chinese clone then derate the mileage.

Answer 3

The best thing to do is buy cars with timing chains, not belts.

Answer 4

Whatever the reason have it replaced.. My friend had a late model VW and the belt broke.. New engine was more than $8k.. 

Answer 5

I assume it's to do with the quality of the belt and the work it has to do. The pulley sizes have an effect upon the stress on the belt. In any event is is advisable to half the recommended mileage for safety's sake. (Haynes manual recommendation.)