PES with a viscosity of 20 cSt or less (with a glass transition temperature of -40 °C) - usually used in electro-hydraulic pushers to drive automation mechanisms operating in the temperature range from -60 °C to +100 °C, for impregnating capacitors and filling piezoelectric sensors in the composition of polishing compounds as coolants; as working fluids in hydraulic systems.

PES with a viscosity of 40-50 cSt at 20 °C (with a glass transition temperature of minus 140 °C), they are a high-tech organosilicon liquid, a mixture of polyethylsiloxanes of predominantly linear structure with a boiling point above 190 °C at a residual pressure of 1.33 * 10² - 3.99 * 10² (1-3 mmHg). Used for the manufacture of greases and greases.

PES with a viscosity of 200-400 cSt are polydiethylsiloxanes with a boiling point above 250 °C at a residual pressure of 133-339 Pa (1-3 mm Hg). Designed for use as a working fluid of vane hydraulic shock absorbers, for operating temperatures from -110 °C to +200 °C.

All PES fluids mix well with mineral and synthetic oils and other organic products, they are used as a base for low-temperature tool and hydraulic fluids and oils, as damping fluids in devices, a dispersing medium in plastic and release lubricants, a component of polishing and cleaning compounds, lubricants in the production of synthetic fibers.

The addition of PES to hydrocarbons improves the low-temperature characteristics of the latter. Mixtures of PES with oils have a lower pour point and a satisfactory viscosity at -50 °C.

Polydiethylsiloxanes can be mixed with petroleum oils in any ratio to improve their lubricating properties. They are suitable for extreme pressure and anti-wear applications. They can be used alone or as mixtures. PES fluids are biologically and corrosively inert.

Low temperature tool oils, frost resistant lubricants and hydraulic filling fluids are formulated from mixtures of polydiethylsiloxanes and mineral oils.

Polydiethylsiloxane fluids are used as operating oil for diffusion vacuum pumps. They differ from organic vacuum fluids in their increased thermal-oxidative stability.

- Polydiethylsiloxanes are transparent liquids with a viscosity of 1.5 to 1 × 106 mm²/s, depending on the degree of polymerisation. These liquids have significantly lower glass transition and solidification temperatures compared to polydimethylsiloxanes, but the effect of temperature on their viscosity is more significant. Polydiethylsiloxanes have a higher viscosity at 20 °C than polydimethylsiloxanes of comparable chain length. The main difference between polydiethylsiloxanes is the extremely low pour point, which is 1.5-2 times lower than that of polydimethylsiloxanes, and reaches minus 140 °C.

- Polydiethylsiloxanes under the PES brand dissolve easily in most organic solvents and, unlike other organosiloxanes, are fully compatible with mineral oils, which has led to their widespread use as a base for oils and greases.

- Replacement of methyl substituents in organosiloxanes with ethyl substituents restricts the freedom of rotation of atoms and groups around Si-O- and Si-C≡ bonds. This leads to an increase in the rigidity of the chains and thereby prevents the realization of helical conformations of the siloxane chains and the complete intramolecular compensation of the dipoles of the polar bonds ≡Si-O-. The branched structure of some polydiethylsiloxanes has the same effect.

- On the other hand, ethyl substituents and branching prevent close packing of chains, which leads to large distances between chains in diethylsiloxanes compared to dimethylsiloxanes and to a decrease in intermolecular interactions.