These two represent the motor oil quality grades and are two US standards, the API standard (the "American Petroleum Institute" standard) and the SAE standard (the "American Society of Automotive Engineering" standard). Yes, you are right, although it is a US standard, but in fact it is a world standard...
Look at the API standard, you just need to remember to sort by alphabet, the better the back!
The API standard is a comprehensive measure of the quality of oil. The quality of oil is divided into SA, SB, SC, SD, SE, SF, SG, SH, SJ, and SL grades from low to high. SL is currently the world's highest quality motor oil.
The grades indicate different qualities, so the oil with the number after the label should be selected, at least SF or higher. Because the better the quality, the better the life of the motorcycle is.
Look at the SAE standard, the bigger the number before and after, the better.
This standard is a measure of the viscosity of an oil and is divided into a single viscosity and a double viscosity. For example: SAE40 (single viscosity), SAE15W-50 (complex viscosity). In the double viscosity, W means winter. The smaller the number before W, the lower the oil resistance is. The higher the number behind W, the better the high temperature oil film retention.
Authentic engine oil, these two standards will be marked at the same time, that is to say, the labeling standards are not complete, certainly not a good engine oil, even if its label is higher!
What grade of oil is used, the description of the vehicle or the casing of the engine will be indicated. For example, if the engine casing is marked with "SF", oil of SF or higher (including SF) can be used. Of course, the higher the oil level, the more expensive the price.
When adding oil, sometimes the repair shop or 4S shop will recommend some brands to mark "XX car special engine oil", saying that this is special, good or something, take a closer look, in addition to this special oil, two standards None of them are marked.