5W-20 5W represents low temperature performance, and 20 represents high temperature performance.
Among them, the low temperature performance has six grades: 0W, 5W, 10W, 15W, 20W and 25W. The higher the numerical value, the worse the low-temperature fluidity, and the corresponding low-temperature values are -35 degrees, -30 degrees, -25 degrees, -20 degrees,-15 degrees,-10 degrees. For example, the lowest temperature in winter in Wuhan is below zero 10 degrees, and I will choose engine oil above 20W.
High temperature performance is the viscosity of engine oil. The bigger the label, the greater the viscosity. Viscosity grades are 20, 30, 40, 50 and 60. The viscosity is not the viscosity when the car is cold, but the viscosity when the engine reaches the normal working temperature.
Wear resistance depends on the quality of the oil and whether the oil you use has passed API (American standard) and ACEA (European standard).
There are SF, SG, SH, SJ, SL, SM, SN, SP and so on in API. S stands for gasoline engine oil, and the farther the letter behind it, the higher the oil quality.
ACEA certification standard is higher than API, and its standard for gasoline engine oil is represented by A, with grades of A 1, A2, A3, A4 and A5. The higher the value, the higher the quality.
Mobil 5W20 mentioned by the subject is the thinnest oil, with low-temperature fluidity of minus 30 degrees and high-temperature viscosity of 20. It has reached the manufacturer's oil standard, so it doesn't need to be changed, just depending on its quality grade.
But then again, it seems that 16 Lang Wei 15S are naturally aspirated engines, so it is not necessary to use synthetic engine oil for all of them. Personally, I think it is a waste of money, and the rest of the money to buy funds is not fragrant.