What is the method for distinguishing automotive oil grades?

[McSophia]

Automotive oil grades are distinguished as follows: 1. The 'S' series represents oil for gasoline engines; 2. The 'C' series represents oil for diesel engines; 3. If both 'S' and 'C' letters are present, it indicates that the oil is suitable for both gasoline and diesel engines. The functions of engine oil are: 1. To alleviate friction and high temperatures; 2. To cool and reduce temperature; 3. To clean and remove contaminants; 4. To dampen vibrations and cushion impacts; 5. To prevent rust and corrosion. Engine oil, also known as engine lubricant, can have the following impacts when using inferior quality oil: 1. It degrades the quality of the oil, reducing its performance; 2. It disrupts the lubrication of precision components such as fuel pumps and injectors; 3. It decreases the power output of the generator set; 4. It affects the combustion efficiency of the engine.

[HarleyFitz]

I always thought distinguishing between oil grades was pretty straightforward, mainly by looking at the labels on oil bottles. The label shows the SAE viscosity grade, like numbers such as 5W-30. The 'W' stands for winter, and the smaller the number before it, the easier it is to start the engine in cold weather. For example, 5W flows smoothly at temperatures as low as -30°C. The larger the number after the 'W,' the better the protection at high temperatures, so using 30 or 40 in summer is fine. There’s also the API grade, like SP or SN, which indicates the oil’s quality and environmental standards. Newer standards like SP are better suited for modern engines to reduce wear. Different cars and seasons require different grades—my old car uses 10W-40 in summer to prevent overheating and switches to 5W-30 in winter for easier starts. Remember not to buy randomly; the manual clearly states the recommended grade. Using the wrong one can lead to sludge or engine wear. I always check the label during each maintenance to confirm.

[LaLillian]

When repairing cars, we often use SAE and API codes to distinguish oil grades. The numbers like 0W-20 on oil bottles indicate viscosity: the number before W in the SAE rating refers to cold-temperature viscosity (0W is ultra-thin for extreme cold), while the number after W represents high-temperature protection (higher numbers like 30 prevent engine overheating). API letters like SP denote performance levels, with newer standards offering better engine cleaning and reduced carbon buildup. Oil type matters too: mineral oils are cheaper but shorter-lived, while synthetics cost more but last longer. Choosing the wrong grade can cause slow starts or accelerated wear—I typically match viscosity using vehicle model and season with simple test tools. The manual's recommendation is most accurate (e.g., many Japanese cars use 5W-20 for fuel efficiency). Don’t just consider price—premium-grade oils save hassle long-term.

[HavenAnn]

The oil grade can be identified by the symbols on the bottle. The label includes the SAE code, such as 5W-30, where 5W indicates better cold-weather startup, and 30 or 40 provides stronger high-temperature protection in summer. The API code, like SN, represents quality standards, with newer versions being better. Oil should be changed with the weather—choose a lower W number for winter and a higher second number for summer. Higher API grades like SP offer better protection for new engines. Always check the manual before purchasing to avoid engine wear. I use a simple method to remember the grade classifications—practical and easy to understand.

[LeDaisy]

Engine oil standards have improved over the years, with grades now differentiated by SAE viscosity such as 10W-40 and API service categories like SP. Older API SL oils suit vintage cars, while newer standards like SP offer cleaner emissions. In SAE grades, lower numbers before the W indicate better cold-weather starting, and higher numbers after provide better hot-weather protection. Always check your manual or online resources for the latest compatible grade during maintenance to extend engine life. Based on my experience selecting oils, I often remind friends not to use the wrong viscosity - high W numbers mean slower winter starts.

[LaHope]

When I first started learning about cars, I couldn't understand engine oil grades, but later I realized the label is key. The SAE number printed on the bottle, like 5W-30, means 5W indicates easy flow in winter, and 30 refers to strong protection in summer. There's also the API code, such as SP, which represents high-quality standards. The way to differentiate is to first check the vehicle manual for the recommended grade, then combine it with weather conditions: use low W numbers in cold areas and high latter numbers in hot areas. Newer API versions are better, so when buying oil, read the packaging text carefully to avoid confusion. These simple steps can prevent engine damage, saving both money and trouble.