Automotive engine temperatures

Viscosity improvers are primarily used in multigrade automotive engine oils, automatic transmission oils, power steering fluids, and gear oils. They also find use in aircraft and some industrial hydrauHc fluids for low temperature use. 

J. Lautikko and N-O. Nyland, Regulated and Unregulated Emissionsfrom Catalyst Vehicles atEow Ambient Temperatures, SAE 930946, Society of Automotive Engineers, Warrendale, Pa., 1993. Good reference for low ambient temperature emissions. 

SAE numbers have been established by the Society of Automotive Engineers to specify ranges of SUS viscosities of oils at SAE test temperatures. Winter numbers (5W, low, 20W) are determined by tests at 0°F. Summer numbers (20W, SOW, etc.) designate the SUS range at 210°F. Table 40.1 is a chart of the temperature ranges. 

This classification was devised by the Society of Automotive Engineers (SAE) in America by dividing the viscosity span into four and giving each of the divisions a number - SAE 20, 30, 40 and 50. The thinnest (SAE 20), for example, covered the range 5.7-9.6cSt specified at 210°F, which was considered to be a temperature typical of a hot engine. (The SAE originally specified temperatures in °F, because they were the convention. Today, temperatures are quoted in °C.)... 

Sparked in large part by this first research on fuel utilization, the petroleum and automotive industries set to work on the problem—the petroleum industry to provide separate summer and winter grade fuels having higher over-all volatility, the automotive industry to provide less critical engines by means of crankcase ventilating systems and better thermostatic control of engine temperatures. 

If the efficiency of an engine increases with increasing temperature, why are conventional automotive engines equipped with radiators to keep them cool ... 

Fig, 6. Change of the axial lead profile with temperature on a base metal oxidation catalyst. [From Rummer et al. (21).] (Reprinted with permission of the Society of Automotive Engineers.)... 

At low power levels NTC thermistors are widely used wherever temperature needs to be controlled or accurately measured, for example in automotive engines, air-conditioning units, hair dryers, and in the medical field for heart catheters, fever thermometers, etc. They are also used to maintain picture stability in television receivers by compensating for increases in the resistance of the beam-focusing coils as temperature rises in the cabinet. The dependence of resistance on the rate of heat dissipation enables them to be used as indicators that fuel tanks are filled to a prescribed level and also in instruments for the measurement of the velocity of fluids. 

Chandler, J. E., Horneck, F. G., and Brown, G. 1.1992. The Effect of Cold Flow Additives on Low Temperature Operability of Diesel Fuels. In Proc., SAE International Fuels and Lubricants Meeting and Exposition, San Francisco, CA. Warrendale PA Society of Automotive Engineers (Paper No. 922186). 

Chandler, J. E., and Zechman, J. A. 2000. Low Temperature Operability Limits of Late Model Heavy Duty Diesel Trucks and the Effect Operability Additives and Changes to the Fuel Delivery System Have on Low Temperature Performance. In SAE Spec. Publ. SP-1563, Gasoline and Diesel Fuel Performance and Additives 2000. Warrendale PA Society of Automotive Engineers (Paper No. 2001-01-2883). 

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