Here’s what engine oil grade represents


Every engine requires an oil to run smoothly and effectively. All engine oils have particular grade that really matters for your engine. You need to understand what is oil grade and what does it mean in order to buy the right grade oil for your engine.

You might have noticed that oil cans have SAE written before the oil grade. SAE stands for Society of Automotive Engineers. However, some oil cans have ‘API’ certified logo. API stands for ‘American Petroleum Institute’; oils which meet the standards of API have this logo attached on their cans. API (American Petroleum Institute) is a joint venture of American and Japanese automobile manufacturers. API certification of oils was created to assist the consumers in identifying oil standards set by automobile manufacturers.

Below we have discussed some engine oil grades and their compatible engines. Commonly used oil grades for gasoline engines are SAE 0W-30, 5W-40, 10W-30, 10W-40 and 20W-50. ‘W’ written in the Oil grade stands for winter. Oil grade typically represents the viscosity of oil. In 5W-40 engine oil, 5 is the low temperature viscosity rating and 40 is the high temperature viscosity rating.

This means that 0W-30 will flow better at low temperature than 5W-30. And similarly 5W-30 will flow better at low temperature than 10W-30 while providing protection at high temperatures. A low viscosity of oil i.e. 0W-30, 5W-40 flows better towards the engine on cold startups.

API certified oil always has three pieces of information on its oil can:

• API rating
• Viscosity grade
• Energy conserving or environmental friendly indicator

Another key information source is the API donut on the back decal of the oil container. It is categorized into three parts illustrating three pieces of information as mentioned above.

The upper part gives information about the API rating; it also determines the performance of the oil i.e., some common characteristics of oil. The concentric circle i.e. the second part gives information about the viscosity of oil as discussed in the above paragraphs. Lower the viscosity leads to rapid flow of oil towards the engine. The lower pipe of the donut gives information whether the oil meets certain energy conserving requirements or to what extent it is environmental friendly. ‘S’ in the top tube of the donut means ‘Service Station oil’ (for gasoline engines particularly), ‘N’ for the current level of service, i.e. to what extent the oil is refined or crude whereas ‘C’ in the top tube of the donut means ‘for commercial engines particularly’. Moreover, 2 written with SAE means for 2-stroke engines and 4 means for 4-stroke engines.1





Understanding oil grade is very important especially when you are running sports engine or weaker engines. Mechanics tend to advice those oils that leave them higher revenues. Understanding oil grades can also help you in identifying fake engine oils by just pouring few droplets of oil in the oil cap in order to test the thickness of the oil. Higher viscosity oil will be stickier in nature than low viscosity of oil. And identically, it will flow like a gooey mixture from the container towards the lid.

Shaf Younus

I'm an Auto Enthusiast, a Computer Science Graduate and above all, Citizen of Pakistan.

  • Ansar Hayat Langah

    Any body suggest me that what kind of oil I use for mehran?

  • Bewildered Crave

    It means if m using 20w-50 in summer the. In winter i shud b using 10w-30 like that?

  • Meesum

    Hey i have suzuki swift 1.3 dlx manual, which engine oil should i use.

  • Blaze Marshal

    Wht oil to use for honda civic reborn 2007. I have done 100,000 km but still condition is very mint of engine. So wht oil should i use?