Every motorbike has a service schedule; the honest answer to “when should I service mine” is “when the manual says, adjusted for how you ride”. This article covers how to read that answer — it deliberately states no specific intervals, because they are model-specific and only the manufacturer’s manual is the authority.
Start with the manual
The service schedule in the owner’s manual lists what to inspect, adjust or replace at each interval. If your bike has no manual, a workshop for the brand or a qualified mechanic can quote the schedule. That document, not a general article, is what to follow.
Vietnam is usually “severe conditions”
Manufacturer schedules assume average use. Dense stop-start traffic, sustained heat, monsoon humidity, flooded streets and dusty roads all shorten the practical life of oil, chains, air filters and brakes. Many riders in this climate service somewhat more often than the manual’s baseline — the right amount more is a mechanic’s judgement, not a guess.
The triggers that override any schedule
Certain findings mean “service now, whatever the book says”: milky or glittering oil (checking-engine-oil-motorbike), brakes that feel spongy or grind (brake-checks-motorbike-vietnam), a chain with stiff links or visible sag, tyres at the wear bars, and any new noise, smell or vibration you cannot explain. Between scheduled services, the bike asking for attention outranks the calendar.
Renters
On a rental, servicing is the shop’s responsibility, not your DIY project. For heavy use, the owner’s practical guidance is periodic checks around every 1,500 km or more of riding — presented as shop guidance, not a manufacturer interval; high-mileage-rental-motorbike-inspection covers that rhythm. Where to have work done is covered in motorbike-service-where-vietnam.
The one-line version
The manual sets the rhythm, Vietnam’s heat and traffic shorten it, and any new noise or fluid cancels the schedule entirely — service by the book and by the bike’s behaviour, not by folklore.