Viscosity refers to the oil’s thickness—the higher the rating, the heavier or more viscous the oil is. Viscosity is a critical factor in how well the oil flows and how much protection it offers. It refers to how easily oil pours at a specified temperature. Thin oils reduce friction in engines and help engines start quickly during cold weather. Thick engine oils are better at maintaining film strength and oil pressure at high temperatures and loads.
The Society of Automotive Engineers developed a scale to represent viscosity of engine oils. Multi-viscosity oils provide the right flow characteristics and lubrication across a wide range of temperatures, from frosty fall mornings to scorching-hot summer afternoons. In most of the vehicles used nowadays, the engines are exposed to the extremities of climates and temperatures. In such situations, the engine has to perform brilliantly in cold as well as warm conditions. To make the engine oil perform well under such differences, some additives (viscosity index improvers) are added to it. Due to this, the engine oil has both winter and nowinter grades, which enables only one kind of oil to be used in all seasons. The SAE designation of such oils generally involves two grades.
Viscosity is notated using the common classification as XXW-YY
The “W” after the first number stands for Winter.
The number preceding the W, rates the oil’s flow at zero degrees Fahrenheit. The lower the numbers, the lesser the oil thickens in cold weather.
The number after the W, indicate viscosity at 100 degrees Celsius, and represent the oil’s resistance to thinning at high temperatures.
For example, oil with 5W-30 grade thickens less than oil with a grade 10W-30 grade in cold weather. Oil with 5W-30 grade thins out more quickly at high temperatures as compared to oils with a 5W-40 grade.
It is crucial to pick the engine oil with the ideal viscosity for the vehicle in order to protect against engine wear. The owners manual of the vehicle should specify which oil viscosity should be used for the engine.
Often the manual may specify multiple options to select from depending on the weather.
Use our “Oil Finder” to find out what viscosity engine oil is suitable for your motorbike.
API and JASO Standards
API stands for American Petroleum Institute and JASO for Japanese Automotive Standards Organisation standard.
The API classification refers to the automobile model years the oil was designed to work on. It speaks to things like lubrication properties, detergent properties, and other factors and gets updated every few years. All API classifications for gasoline engines start with an S, followed by the letter A through the current N standard.
JASO introduced two standards for motorcycle oils based on the SAE’s (Society of Automotive Engineers Clutch Friction Test: MA for bikes with wet clutches and MB for bikes with automatic transmissions.