| Characteristics | Standard | Description |
| Viscosity | DIN 51561 | Measure for the inner friction of liquids |
| ISO VG | DIN 51519 | Assignment of oils into viscosity classes |
| Operating temperature | Temperature range of the optimal performance | |
| Flashing point | DIN ISO 2592 | Lowest temperature at which the vapour-air mixture ignites through extraneous ignition |
| Solidifying point | DIN ISO 3016 | The lowest temperature at which the oil is still just capable of flowing |
When selecting a lubricating oil, the base oil is of decisive importance. Mineral oils, synthetic hydrocarbons (polyalphaolefins = PAO),
ester, polyglycols and silicone oils differ considerably in their physical properties and chemical characteristics.
| Properties | Mineral oils | Synthetic hydrocarbons (PAO) | Ester oils | Polyglycol oils | Silicone oils |
| Density 20°C [g/ml] approx.: | 0,9 | 0,85 | 0,9 | 0,9 - 1,1 | 0,9 - 1,05 |
| Solidifying point [°C] approx.: | -40 -> -10 | -50 -> -30 | -70 -> -35 | -55 -> -20 | -80 -> -30 |
| Flashing point [°C] approx.: | < 250 | < 200 | 200 -> 270 | 150 -> 300 | 150 -> 350 |
| Oxidation resistance | - | + | + | + | ++ |
| Thermal stability | - | + | + | + | ++ |
| Compatible with plastics | + | + | - | type-dependent | + |
The miscibility of different oils is influenced considerably by the base oils and must be taken into account correspondingly when
selecting the lubricant.