VNIINP-50-1-4u oil is a high-quality synthetic diether oil obtained by chemical synthesis. It contains a composition of effective additives and, in terms of operational characteristics, outperforms VNIINP-50-1-4f oil. The oil has high (up to 200°C) thermo-oxidative stability with an allowable overheating up to 225°C.

Thanks to its exceptionally efficient viscosity-temperature properties, the VNIINP-50-1-4u oil forms a very strong film on friction surfaces at operating temperatures above 100°C, which does not break down even in the most extreme thermal conditions. Additionally, with a low freezing point of -60°C, it can be effectively used in extreme conditions of harsh winters. It is intended for modern gas turbine engines and new prospective equipment.
The VNIINP-50-1-4u oil is fully compatible with the VNIINP-50-1-4f oil and can replace it without requiring replacement of structural materials and rubber.
The VNIINP-50-1-4u oil mixes well with mineral oils. With its high dissolving ability, the oil can dissolve sludge and varnishes, remove deposits that have formed in the engine as a result of the use of other oils, and maintain the cleanliness of engine parts.
The VNIINP-50-1-4u oil has undergone a full cycle of acceptance tests, including flight tests. They have shown that using VNIINP-50-1-4u oil instead of VNIINP-50-1-4f oil significantly increases the engine's working life.
The oil is used as one of the main oils in aviation technology.
It is recommended for prospective equipment.
Technical specifications of VNIINP-50-1-4u oil (TU 38.401-58-12-91)
| Indicator name | GOST (TU) standard |
|---|---|
| Appearance | Clear, light liquid |
| Kinematic viscosity, mm2/s: | |
| At 100°C, not less than | 3.2 |
| At -40°C, not more than | 2700 |
| At -50°C, not more than | 8500 |
| Temperature, °C: | |
| Flash point (open cup), not lower than | 204 |
| Pour point, not higher than | -60 |
| Acid number, mg KOH/g, not more than | 0.25 |
| Content of water-soluble acids, bases, mechanical impurities, water | Absent |
| Thermo-oxidative stability, hours at 200°C (air flow rate of 10 dm3/hr) | 50 |
| Indicators after oxidation: | |
| Kinematic viscosity, mm2/s, at 100°C, not more than | 3.7 |
| Acid number, mg KOH/g, not more than | 4.5 |
| Mass fraction of insoluble sediment in iso-octane, %, not more than | 0.15 |
| Corrosion on plates, g/m2: | |
| Steel XH15 | ±1.0 |
| Copper M1 and M2 | ±4.0 |
| Aluminum alloy AK4 | ±1.0 |
| Density at 20°C, kg/m3, not more than | 926 |
| Tribological characteristics on CHMT at (20±5)°C: | |
| wear rate under axial load of 196 N, not more than | 0.45 |

