All owners of Yamaha outboards should learn how to check oil. Depending on the tachometer your engine uses, the oil level indicator could be digital or analog. Look to see if all three blocks (digital) or all three lights (analog) are glowing green. This indicates that there is plenty of oil in the main and reserve tanks.
If you see a yellow light, then you need to add more Yamaha outboard oil. On yellow, your engine oil tank may be full, but chances are your reserve is empty. You don’t ever want your tachometer to flash red; that indicates a fill-up is needed immediately. To ward off accidents, make sure to bring extra oil on long excursions.