'Chain for life' is one of the biggest myths in modern motoring. Several common engines have well-documented timing system failures — and some belts now run inside the oil ('wet belts'), with their own issues.
Ford 1.0 EcoBoost wet belt
Wet belt degrades and sheds rubber particles into the oil pump strainer. Recommended change at 100k miles or 10 years — and don't skip oil services.
BMW N47 timing chain
Rear-mounted chain (gearbox end) — needs engine out for replacement. Stretched chains cause rattle at cold start. Service early or pay massively later.
PSA 1.2 PureTech wet belt
Same issue as the EcoBoost. Earlier replacement (60k miles) is now recommended. Wet belt failure destroys the engine.
VAG 2.0 TDI chain (early)
Older PD/CR diesels had chain tensioner issues. Stretched chain symptoms = rattle + advanced/retarded cam codes.
Honest schedule advice
Don't trust 'lifetime' — ask your mechanic for the real-world interval on your specific engine code.