TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: In method (m1), the sequence of treatment steps are performed in the sequence of first removing the oil insoluble impurities from the crude oil; subsequently removing the oil soluble impurities from it; subsequently neutralizing it by a de-acidification; and afterwards drying, bleaching and filtering, which are followed by a de-stearinization or deodorization of the oil. The pre-treatment step of removing oil insoluble impurities involves a combination of settling and filtration or centrifugation of the crude oil; eliminating free fatty acids and substances foreign to the glycerides of pure oil contained in the oil; eliminating impurities including proteins, gums, resins, photosphatides, coloring matters, hydrocarbons, ketones, aldehydes and/or peroxide compounds in true solution or in a state of colloidal suspension; and combining this cleaning stage with neutralization of the free fatty acids with caustic soda resulting in the formation of soap, where a large proportion of the impurities is removed. The neutralization step involves the addition of a dense caustic soda solution of approximately 200 degrees Be, preferably in excess of 60-80%, additionally resulting in both a purification of the oil, as well as in an at least partial bleaching or decolorization, thus facilitating the subsequent bleaching. The excess of caustic soda is applied in such a way that an over-saponification takes place resulting in the formation of soap. The created soap is removed by settling or centrifugation, after which some weak caustic soda, in particular 6-8 degrees Be is added to clear out the particles of suspended soap and remove at least a part of the remaining coloring matters. At the end of the cleaning step, a hot water washing is carried out at at least 95 degrees C, preferably of substantially 98 degrees C. The hot water washing step is performed repeatedly, so as to at least substantially eliminate the traces of caustic soda, soap and different particles for reducing the acidity of the oil to at least less than 0.05%. The drying step involves the removal of moisture in order to avoid hydrolysis at an elevated temperature of at least 80 degrees C, preferably of substantially 90 degrees C in closed vessels and under vacuum, preferably of substantially 30 mmHg. The bleaching step is performed by selecting a material with high active surface, mixing the materials with the oil and subsequently filtering the mixture thus achieved to remove different particles and coloring matters. The selection of the material is operated among materials such as bleaching earths and active carbon. The materials, preferably bleaching earth is mixed with the oil under vacuum, where the mixture is subsequently filtered after a period of time of less than 30 minutes. The de-stearinization step is performed by filtration in order to achieve the necessary CFPP (Cold Filter Plugging Point) of the cottonseed oil and its mixtures with diesel fuel especially at low temperatures, particularly below 3 degrees C, more particularly below 0 degrees C; by removal of the undesired constituents from the oil, where the oil is cooled for a prolonged period at temperatures some degrees below that at which the oil is required to remain clear and then filtered; and by successively a) pre-cooling the oil at T1 with agitation during t1, b) cooling and crystallization at T2 without agitation during t2, c) cooling and crystallization at T3 without agitation during t3 and d) filtering during t4 (where T1, T2, T3 are the temperatures and t1, t2, t3, t4 are the time intervals for the intermediate stages), which are vary according to the season and the low temperatures of a given region, resulting in the cottonseed oil achieved with this procedure, where the addition of the proper additive does not affect the CFPP value of diesel fuel. The parameter value T1 is 5 degrees C and t1 is 5 hours correspondingly, T2 is 0 degrees C and t2 is 12 hours correspondingly, T3 is -7 degrees C and t3 is 24 hours correspondingly and t4 is 8 hours. The cooling is performed sufficiently slowly to enable the components with higher melting point to form well built crystals. The cooling and filtration are carried out in a well insulated room equipped with refrigeration. The deodorization step is performed in order to remove undesirable substances of the oil by passing a current of dry steam through the oil at high temperatures or 200-225 degrees C under vacuum of the order of 6-30 mmHg resulting in the selective removal of the undesirable odoriferous compounds and substances such as peroxides and broken down the molecules. In the production of refined oil the additive (A1) is added in the amount of 400-800 parts per minutes in mixture of cottonseed oil (10%) and diesel fuel (90%). Preferred Components: The high active surface materials are selected to retain the coloring substances by adsorption resulting in decoloration by adsorption, in which these adsorbents have the capacity to adsorb on their surface not only the coloring components but also other suspended substances such as gums, resins and certain oil degradation products, that affect the correct diesel engine operation. The removed components belong to either substances which are present in the crude oil and are responsible for the characteristic odor such as unsaturated hydrocarbons, carotenoid pigments, terpenes or substances arising from deterioration of oil quality during storage or processing such as hydrocarbons, free fatty acids resulting from glyceride hydrolysis, ketones and aldehydes as products of fatty acids degradation and peroxides produced during oil storage, possibly from oxidized molecules break-down and enzymatic activities. The ingredients of the additive composition is diethyl ether (CH3CH2OCH2CH3) or an ether of low molecular weight (1-2, preferably 1 vol./vol.%), acetone (CH3COCH) or another low molecular weight ketone such as methyethyl ketone (15-25, preferably 10 vol./vol.%), toluene (CH3C5H6) (5-15 vol./vol.%), hexane or another low molecular weight saturated hydrocarbon (15-25, preferably 20 vol./vol.%), turpentine (oil) (15-25, preferably 20 vol./vol.%), methyl alcohol (CH3OH) or another low molecular weight alcohol (15-25, preferably 20 vol./vol.%) and ethyl alcohol (CH3CH2OH) or another low molecular weight alcohol such as isopropylic alcohol (5-10, preferably 9 vol./vol.%). EXAMPLE - No suitable example given.