Look up oil capacity for a Vietnamese underbone and you may find two different litre figures for the same engine. Both are correct - they measure different jobs. Honda VN publishes both for its underbone range (retrieved 23 September 2026).
The two numbers, verified
- Wave Alpha, Blade, Wave RSX: 0.8 L drain / 1.0 L overhaul
- Future 125 FI: 0.7 L drain / 0.9 L overhaul
- Super Cub C125: 0.80 L drain / 0.85-1.00 L overhaul
- CT125: 0.8 L drain / 0.85-1.0 L overhaul
- Winner R and CBR150R: 1.1 L drain / 1.3 L overhaul
What they mean
Drain capacity: how much oil to refill after draining the sump at a normal oil change - the number you use at every service. Overhaul capacity: the total the engine holds when refilled completely dry after being disassembled - more oil sits in passages and cavities that a drain never empties. Overfilling to the overhaul figure at a normal change is a real and common mistake.
Why it matters in Vietnam
The commuter class sumps are tiny: 0.7-0.8 litres is roughly a large water bottle. That makes underbone oil changes fast and cheap - one reason the format thrives here - but also means the oil works hard per litre. Our oil-checking and choosing guides cover grade and level discipline, and the home-change guide covers doing it yourself. Yamaha publishes no equivalent capacities for the Sirius or Exciter on the retrieved pages - do not copy Honda figures onto a Yamaha.
Rental note
Renters should not need to touch oil on short rentals - the rental business covers basic maintenance like oil checks. Our rental care guide covers what to inspect; contact us to confirm current availability of any model.