Title: Valve actuator
Content:  In Siberia, temperatures down to – 60 °C may occur, and in technical process plants + 100 °C may be exceeded. Using the proper lubricant is crucial for full operation under these conditions. Greases which may be used at room temperature can become too solid at low temperatures for the actuator to overcome the resistance within the device. At high temperatures, these greases can liquify and lose their lubricating power. When sizing the actuator, the ambient temperature and the selection of the correct lubricant are of major importance.
Title: Space tribology
Content:  Liquid lubricants for space applications need to have low vapor pressure (volatility) in order to withstand the high vacuum on orbit. Suitable lubricants include perfluoropolyethers, cyclopentanes and polyalphaolefins, mostly in the form of base oils for lubricating grease. Since the rate of evaporation increases with temperature, the use of liquid lubricants is often limited to temperatures below 100 °C. On the other side of the spectrum, the viscosity of liquid lubricants increases with decreasing temperature; i.e., the lower the temperature, the more viscous the lubricant (see also viscosity index). Thus, the use of liquid lubricants is limited to temperatures of around -40 °C.
Title: Lubricant
Content:  Both gas and liquid lubricants can transfer heat. However, liquid lubricants are much more effective on account of their high specific heat capacity. Typically the liquid lubricant is constantly circulated to and from a cooler part of the system, although lubricants may be used to warm as well as to cool when a regulated temperature is required. This circulating flow also determines the amount of heat that is carried away in any given unit of time. High flow systems can carry away a lot of heat and have the additional benefit of reducing the thermal stress on the lubricant. Thus lower cost liquid lubricants may be used. The primary drawback is that high flows typically require larger sumps and bigger cooling units. A secondary drawback is that a high flow system that relies on the flow rate to protect the lubricant 
Title: Lubricant
Content: A high boiling point and low freezing point (in order to stay liquid within a wide range of temperature) ; A high viscosity index ; Thermal stability ; Hydraulic stability ; Demulsibility ; Corrosion prevention ; A high resistance to oxidation A good lubricant generally possesses the following characteristics:
Title: Extreme tribology
Content:  and self-adjust. These materials include structural/lubricating integrated material, anti-radiation lubricating material, conductive or insulation lubricating material, etc.At low temperatures and in cryogenic environments, liquid lubricants can solidify or become highly viscous and not be effective. On the other end, solid lubricants have usually been found to be better than liquid lubricants or greases. The most common solid lubricants for cryogenic temperature are polytetrafluoroethylene, polycarbonate, tungsten disulphide (WS2), and molybdenum disulphide (MoS2). In addition, ice could be a possible lubricant for deformation in cryogenic environments which provides a method of self-lubrication in the sense that no active mechanism is needed to supply a lubricant.
Title: Pour point depressant
Content:  Pour point depressants are used to allow the use of petroleum based mineral oils at lower temperatures. The lowest temperature at which a fuel or oil will pour is called a pour point. Wax crystals, which form at lower temperatures, may interfere with lubrication of mechanical equipment. High-quality pour point depressants can lower a pour point of an oil additive by as much as 40°C.
Title: Tribology
Content: Weather conditions; ; Local thermal factors (like for car engines or refrigeration pumps); ; Energy dissipation due to rubbing between surfaces. Temperature and pressure are two fundamental factors to evaluate when choosing a lubricant instead of another. Consider the effects of temperature initially. There are three main causes of temperature variation that can affect the behavior of the lubricant:  In order to classify the various lubricants according to their viscosity behavior as a function of temperature, in 1929 the viscosity index (V.I.) was introduced by Dean and Davis. These assigned the best lubricant then available, namely the oil of Pennsylvania, the viscosity index 100, and at the worst, the American oil of the Gulf Coast, the value 0. To determine the value of the intermediate oil index, the following procedure is used: two reference oils are chosen so that the oil in question has the same viscosity at 100 °C, and the following equation is used to determine the viscosity index is a constant that describes the relationship between viscosity and pressure.
Title: Dry lubricant
Content:  Polytetrafluorethylene (PTFE) is widely used as an additive in lubricating oils and greases. Due to the low surface energy of PTFE, stable unflocculated dispersions of PTFE in oil or water can be produced. Contrary to the other solid lubricants discussed, PTFE does not have a layered structure. The macro molecules of PTFE slip easily along each other, similar to lamellar structures. PTFE shows one of the smallest coefficients of static and dynamic friction, down to 0.04. Operating temperatures are limited to about 260 °C.
Title: Pour point
Content:  The pour point of a liquid is the temperature below which the liquid loses its flow characteristics. It is defined as the minimum temperature in which the oil has the ability to pour down from a beaker. In crude oil a high pour point is generally associated with a high paraffin content, typically found in crude deriving from a larger proportion of plant material. That type of crude oil is mainly derived from a kerogen Type III.
Title: Dropping point
Content:  The dropping point of a lubricating grease is an indication of the heat resistance of the grease and is the temperature at which it passes from a semi-solid to a liquid state under specific test conditions. It is dependent on the type of thickener used and the cohesiveness of the oil and thickener of a grease. The dropping point indicates the upper temperature limit at which a grease retains its structure though is not necessarily the maximum temperature at which a grease can be used. Dropping point is used in combination with other testable properties to determine the suitability of greases for specific applications and for use in quality control.

Question: the lowest temperature at which a lubricant will flow is called the?
Answer: pour point.