ISO 3448
ISO VG 220 at temperature
ISO VG 220 is the industrial gear oil most maintenance sheets mean by “220” or “220 EP.” It is a 40°C grade. The mesh never sees 40°C just because the drum says so.
The ISO 3448 window at 40°C is 198 to 242 mm²/s. The midpoint used below is 220.
In enclosed spur and helical reducers of moderate speed, in a lot of circulating systems, and as the lighter option on some worm-gear plates, 220 is the default someone reaches for. It is the right reach when the plate or AGMA 9005 says so. It is a guess when the sump runs hot and nobody has looked at the viscosity that is actually in the mesh.
| °C | VI 95 | VI 150 |
|---|---|---|
| 20 | 861 | 670 |
| 40 | 220 | 220 |
| 60 | 78.3 | 91.8 |
| 80 | 35.2 | 45.7 |
| 100 | 18.7 | 25.9 |
The 100°C figures on this page are illustrative. ISO 3448 specifies the grade at 40°C only. Each column is the viscosity of an oil that hits the grade midpoint at 40°C and the stated viscosity index, solved with ASTM D2270, then moved to other temperatures with the ASTM D341 Walther equation (constant 0.7). A dash means that viscosity index would put the oil below 2 mm²/s at 100°C, where ASTM D2270 does not define VI. Use the data sheet in the converter when you have one.
Put the data sheet’s own 40°C and 100°C numbers into the two-point calculator. The viscosity index of those two points is explained on the viscosity index page.
Where this grade shows up
A mineral oil near VI 95 and a PAO near VI 150 with the same VG 220 name are different fluids at 80°C. The table is that difference for the midpoint oil. Additive type, EP level, and compatibility with the seals are outside the grade. The gearbox page is the selection method. Worm drives often step up to 460 or 680.
Compare branded products on oilviscositychart.com. The other heavy grades are ISO VG 320 and ISO VG 460.
Questions
What is the ISO VG 220 range?
198 to 242 mm²/s kinematic viscosity at 40°C. The midpoint is 220 mm²/s. ISO 3448.
What is ISO VG 220 at 100°C?
ISO 3448 does not say. A VI 95 mineral oil and a VI 150 synthetic with the same 40°C midpoint have different 100°C viscosities. The table on this page is that illustration. The data sheet is the measurement.