Interactions between modern engine oils and reformulated fuels

paper presents the reasons and tendencies of the changes of the quality requirements of engine oils and fuels having significant influence also on the interactions between the two types of products (operating materials). The possibilities of grouping the relationships between engine oils and engine fuels are summarized. Interactions between engine oils and engine fuels are presented with the use of some actual examples. The paper presents some results of the authors' experiments about the possibilities for improving the interactions between engine oil and fuels (e. g.: to prevent increase of viscosity of lubricating oils by cold and black sludge formation in gasoline engines applying new types of detergent-dispersant additives; in direct injection diesel engines by application of appropriately chosen DD-additive package, in order to prevent increase of viscosity of engine oils and therefore higher fuel consumption because of higher soot loading caused by EGR, longer drain interval, etc.; both engine oils contain reduced sulphate ash, chlorine, phosphorus and sulphur). The final conclusion is that solution of the numerous problems originating in the multi-faceted interactions will only be possible by optimizing the methods defined on the basis of technical, environmental and economic considerations of lubricating oils, fuels and engines themselves.