How is full synthetic oil represented by letters?
2 Answers
Full synthetic oil does not have a letter designation. The API of the oil only represents the oil grade, and there is no necessary connection between the oil grade and full synthetic oil. The SN grade is currently the highest grade, but SN grade includes both full synthetic and semi-synthetic oils. There are two labels for oil: one is SAE and the other is API. SAE is used to indicate the viscosity of the oil, while API is used to indicate the grade of the oil. API is the quality level of the oil as designated by the American Petroleum Institute. The API consists of two letters: the first letter is S for gasoline engines or C for diesel engines. If both S and C are marked, it means the oil is suitable for both gasoline and diesel engines.
You asked how to represent full synthetic oil with letters, which reminds me of my usual car maintenance experiences. As a seasoned driver, I've changed quite a bit of engine oil. Full synthetic oils are usually marked with API classification letters like SN or SP on the packaging—these are high-performance standards for gasoline engines. The 'S' prefix stands for gasoline oils, and the combination of numbers or letters indicates the performance level, with SP currently being the top tier. SAE viscosity such as 5W-30 may also be labeled, but full synthetic oils will explicitly state 'Full Synthetic' in text. The letters help you identify the oil's quality. The benefits of full synthetic oil include stronger engine cleaning, reduced carbon buildup, and extended engine life. Since using it, my engine starts more smoothly, especially in winter. I recommend changing it every 5,000 to 8,000 kilometers—don’t skimp by buying low-quality oil, as it can save you a lot on repair costs.
