Oil Viscosity
Viscosity is the best-known characteristic of lubricants. It is a measure of the internal friction, the fluidity of an oil. When an oil is cold, internal friction is high (high viscosity); the warmer the oil, the lower the internal friction (low viscosity).
SAE Viscosity Grades
The viscosity of motor vehicle oils are described by the SAE (Society of Automotive Engineers) viscosity grades. The standards establish the viscosity measuring temperature, the viscosity limits and the distribution of viscosity grades. Oils with established viscosity limits in the cold state have an additional letter W (Winter).
In the hot state the viscosity of the engine oil is defined at 100 ° C for all SAE classes, but this does not correspond to the practice of oil. Therefore, the high-temperature viscosity of the oil at high shear rate and high temperature (HTHS) is also determined.
SAE J300 Viscosity Grades for Motor Oils, 2015 Version11
SAE grade |
Low temperature viscosity | High temperature viscosity | |||||
Dynamic viscosity (scrollability)1) | Pumpability2) | Viscosity at low shear rate, at 100 оС (kinematic viscosity)3) mm2/s | Viscosity at high shear rate (HTHS), at 150 оС, mPa·s | ||||
mPa·s | оС | mPa·s | оС5) | min | max | min | |
0W | 6200 | – 35 |
60000 |
– 40 | 3,8 | – | – |
5W | 6600 | – 30 | – 35 | 3,8 | – | – | |
10W | 7000 | – 25 | – 30 | 4,1 | – | – | |
15W | 7000 | – 20 | – 25 | 5,6 | – | – | |
20W | 9500 | – 15 | – 20 | 5,6 | – | – | |
25W | 13000 | – 10 | – 15 | 9,3 | – | – | |
8 | – | – | 4,0 | < 6,1 | 1,7 | ||
12 | – | – | 5,0 | < 7,1 | 2,0 | ||
16 | – | – | 6,1 | < 8,2 | 2,3 | ||
20 | – | – | 6,9 | < 9,3 | 2,6 | ||
30 | – | – | 9,3 | < 12,5 | 2,9 | ||
40 | – | – | 12,5 | < 16,3 | 2,96) | ||
40 | – | – | 12,5 | < 16,3 | 3,77) | ||
50 | – | – | 16,3 | < 21.9 | 3,7 | ||
60 | – | – | 21,9 | < 26,1 | 3,7 | ||
1) According to ASTM D 5293
2) According to ASTM D 4684 3) According to ASTM D 445 4) According to ASTM D 4683 або ASTM D 4741 або ASTM D 5481 5) pumping temperature should be about 5 оС lower than the cold start temperature 6) for 0W/5W/10W-40 7) for 15W/20W/25W-40 |