Motor oil numbers can be quite confusing. After all, the average person doesn’t know what all those numbers mean, or which number is the right one to choose when they go to buy oil for their vehicle. But understanding motor oil number meaning is actually quite simple once you understand the basics.
Motor oil numbers are broken into two parts – the viscosity rating, and the API rating. The viscosity rating is the first number, and the API rating is the second.
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Viscosity Rating
The viscosity rating is the first number in the motor oil number. This number is a measure of the oil’s ability to flow at different temperatures. A higher number indicates a thicker oil, which is better for high temperatures, while a lower number indicates a thinner oil, which is better for cold temperatures.
For example, a motor oil with a viscosity rating of 5W-30 is thicker than a motor oil with a viscosity rating of 10W-40. In general, it’s best to use the viscosity rating recommended by your vehicle’s manufacturer, as this will ensure that your engine gets the proper amount of lubrication.
API Rating
The second number in the motor oil number is the API rating. This number indicates how well the oil will protect your engine from wear and tear. A higher number indicates a better protection, so look for a motor oil with a higher API rating if you want the best protection for your engine.
API ratings are divided into two categories – Service Category and Service Symbol. The Service Category is the first letter of the API rating, and it indicates the oil’s performance level. The Service Symbols are the second and third letters of the API rating, and they indicate the oil’s intended use.
Service Categories
The Service Categories are designated by the first letter of the API rating. In general, the higher the letter, the better the protection provided by the oil. The categories are as follows:
- SA – Used in older engines that do not use catalytic converters.
- SB – Used in older engines that do use catalytic converters.
- SC – Used in newer engines that do not use catalytic converters.
- SD – Used in newer engines that do use catalytic converters.
- SE – Used in newer engines that are fitted with turbochargers or other high-performance components.
- SF – Used in older engines that are fitted with turbochargers or other high-performance components.
- SG – Used in the latest engines that are fitted with turbochargers or other high-performance components.
Service Symbols
The Service Symbols are designated by the second and third letters of the API rating. These letters indicate the oil’s intended use. The symbols are as follows:
- SJ – Used for gasoline engines.
- SH – Used for diesel engines.
- CF – Used for gasoline engines that are fitted with catalytic converters.
- CF-4 – Used for diesel engines that are fitted with catalytic converters.
- CD – Used for gasoline engines that are fitted with turbochargers or other high-performance components.
- CD-4 – Used for diesel engines that are fitted with turbochargers or other high-performance components.
So the next time you go to buy motor oil, you should be able to more easily understand the motor oil number meaning. Just remember to use the viscosity rating and API rating recommended by your vehicle’s manufacturer and you should be good to go.
