Monograde Engine Oil
Single-grade oils for older engines, some transmissions and equipment whose manual specifies them. Still required across parts of an ageing plant fleet.
Features
- One viscosity at operating temperature and no viscosity index improver, which is what some older engines and hydraulic-transmission systems were designed around.
- Used seasonally in some fleets, with a lighter grade in winter and a heavier one in summer.
- Specified in certain wet-brake and clutch applications where a multigrade changes friction behaviour.
- Still specified because older equipment does not disappear from a fleet when a new machine arrives, and the manual for that machine governs its fill whatever the yard has standardised on elsewhere.
Specifications
| Figure | Typical range | Unit | Why it matters |
|---|---|---|---|
| Viscosity grade | 30 / 40 / 50 | single-grade designation, no cold-start rating | |
| Kinematic viscosity at 100 degrees C | 9.3 - 21.9 | mm2/s | the property behind the grade number, and the three grades do not overlap |
| Application | engine / transmission / final drive | the same grade number is used in very different systems | |
| Seasonal use | summer fill | monograde fleets often change grade twice a year |