Study of the detergent action and the effectiveness of succinimide additives in motor oils

Abstract

CONSIDERABLE attention has recently been given to developing suceinimide additives for motor oils. The detergent effect of these additives is due to their dispersing action, in which the ability to prevent the coagulation of highly dispersed particles (products of incomplete combustion of fuel and oxidation of oil) and peptize aggregated particles is borne in mind; this increases the dispersion of the oily suspension and helps to stabilize it. I t is shown that loose residues formed on the metal surfaces of the engine may be kept in suspension by dispersing additives [1]. These views concerning the mechanism of dispersing action of additives used in motor oils are to a known extent hypothetical and have been confirmed experimentally only to a small extent. To study the mechanism of detergent effect of succinimide additives we used laboratory methods which enabled us to determine the effectiveness oi the stabilizing [2, 3] and dispersing effect of these additives. The effectiveness of the stabilizing action1 is estimated by the stability on centrifuging of a labelled carbon black suspension in oil with an additive used. Precipitation of the labelled carbon black is controlled by measuring from time to time the radioactivity of the upper layer of the centrifuged suspension. Results of investigations are given in percentages: the radioactivity of the upper suspension layer before centrifuging was taken as 100%. The use of this method made it possible to establish that the detergent effect of suceinimide additives also includes the stabilization of particles in the engine oil [3]. To investigate and evaluate the effectiveness of dipersing action of additives for engine oils, we developed two new laboratory methods. One is meant to evaluate the ability of additives to wash off the polar carbon black particles adsorbed on the metal surface and the other, to determine the ability of additives to reduce the dimensions of impurity particles. The first method is based on the principle of producing adhesive contact between the polar carbon black particles and metal powders during filtration of the carbon black suspension in oil through a porous powder layer used