In the North-East region of USSR number of days in a year with mean day temperature lower than minus 30°C is made up off 28-35,6 % from the total continuation of the year i.e. the mean day temperature of air during 1/3 of the year remains to lower values than at which it is possible to start the engine without using any means for making it easy to start.Serially produced heaters in the working regime of maintaining the warm condition of the engine, ensure the keeping of temperature of cooling off liquid at the level of 63-78°C. Evident that fact, that keeping of temperature at certain level is determined by the condition of effective work of heaters of cabin (saloon) (Tcool.liq=80°C) i.e. the pointed outs are advisable in case of presence of driver and passengers in the cabin, in other cases the stated level of maintaining temperature of cooling off liquid may be sufficiently reduced. Question arises: what range of temperature may be taken as optimum in the work of heater in automatic regime of maintaining temperature of cooling off liquid of engine.On the basis of analysis of dynamics of pre-starting heating of diesel engines of different models, obtained by the results of tests in the North Auto test station of Central Auto Proving Ground, the authors single out it's main stages and make conclusion about optimum, indivisible connection of energy loss with possibility of ensuring the cold start of engine, significance of temperature of cooling off liquid.In further discussed the heat loss and energy waste in the work of heaters in local regime “heating of cold engine” and in regime “keeping of warm state of engine” in the level of 63-78°C.Due to specific condition of work of vehicle in the North and on the basis of carried out analysis, by the authors there proposed in the capacity of basic optimization regime of keeping warm state of engine.At this, there discussed the basic arguments showing the evidence, in their opinion, to the use of proposed regime and basic way of further optimization of work of heater in specified regime.The adopted conception proposed by the authors in combination with it's further development, to the set forth direction, allows to raise the reliability of cold starting of engine, reduce it's preparatory time towards the taking of load (start of motion), raise it's longevity.