How to Choose Industrial Gear Oil Viscosity and Type
By the PCG Technical Desk · Updated 27 September 2026
1. Viscosity
- Low speed, high torque, hot environment: VG 320–680 (e.g. Servomesh SP 320, 460).
- Typical helical/bevel reducers: VG 150–320, with VG 220 the most common (Servomesh SP 220).
- High-speed units / cold conditions: VG 68–150.
The standard method (for example AGMA guidance) picks viscosity from pitch-line velocity and operating temperature. Too thin, and gears scuff and pit. Too thick, and they run hot and waste power.
2. Type
- EP mineral gear oil for most enclosed industrial gears under load (Servomesh SP).
- DIN 51517-3 CLP / micropitting requirement: choose a grade listing it (IOCL lists Servomesh Plus and Servosyngear AMP).
- Synthetic PAO for extreme temperatures or extended drains (Servosyngear).
3. Worm gear oil selection
Worm gears slide more than they roll, and the wheel is usually bronze. Some sulphur-phosphorus EP additives can attack bronze at high temperature. Many OEMs specify a compounded oil or a PAG synthetic for worm drives. IOCL recommends compounded Servocyl C oils for worm gears and lists PAG-based Servosyngear HVI for worm gear lubrication. Never mix PAG with mineral oils.
Recommended SERVO grades
FAQs
Follow the OEM. Commonly a compounded mineral oil (IOCL lists Servocyl C) or a PAG synthetic (IOCL lists Servosyngear HVI) in VG 220–680.
