SAE Viscosity Grade Selection
Viscosity is a measure of an oil’s resistance to flow at various temperatures. The SAE Viscosity Grade system is defined in SAE Standard J300 that designates a viscosity range with a grade number. Lubricants with two grade numbers separated by a “W,” such as 15W-40, are classified as multigrade, while those with a single number are monograde. The higher the number, the higher the viscosity.
The viscosity requirements associated with each SAE viscosity grade are listed in Table "SAE Viscosity Grades for Engine Oils (SAE J300)." This information is important in selecting the best viscosity grade for the anticipated ambient temperature range at which the engine will start and operate. Use it only as a guideline, since actual operating conditions of the engine may determine the lowest practical temperature at which an engine will start and operate. Note that grades designated with a “W” are required to meet both low temperature and high temperature viscosity requirements.
Table 1, SAE Viscosity Grades for Engine Oils (SAE J300)
| SAE Viscosity Grade | Viscosity (cP) at Temp. (°C), Max | Viscosity (cSt) SAE ASTM D 445 (100°C) | High Temperature High Shear Rate Visc @ 150°C & 105 sec | ||
|---|---|---|---|---|---|
| Cranking ASTM D 5293 | Pumping ASTM D 4684 | Min | Max | ||
| 0W | 6200 at -35 | 60,000 at -40 | 3.8 | — | — |
| 5W | 6600 at -30 | 60,000 at -35 | 3.8 | — | — |
| 10W | 7000 at -30 | 60,000 at -30 | 4.1 | — | — |
| 15W | 7000 at -20 | 60,000 at -25 | 5.6 | — | — |
| 20W | 9500 at -15 | 60,000 at -20 | 5.6 | — | — |
| 25W | 13,000 at -10 | 60,000 at -15 | 9.3 | — | — |
| 20 | — | — | 5.6 | 9.3 | >2.6 |
| 30 | — | — | 9.3 | 12.5 | >2.9 |
| 40 | — | — | 12.5 | 16.3 | >3.7 |
| 50 | — | — | 16.3 | 21.9 | >3.7 |
| 60 | — | — | 21.9 | 26.1 | >3.7 |
Table 1, SAE Viscosity Grades for Engine Oils (SAE J300)
For standard temperature limits of each viscosity grade; see the following figure.
