Possible ways of synthesizing low-ash magnesium-containing additives for motor oils by using magnesium oxide of various origins in the synthesis have been considered: carbonation of neutral magnesium alkylsalicylate with magnesium oxide to produce a magnesium-magnesium additive and carbonation of neutral magnesium alkylsalicylate with calcium hydroxide to form a magnesium-calcium additive. Samples were obtained with an alkalinity level of 307-317 mg KOH/g and a viscosity not exceeding 130 mm(2)/s, values that meet the requirements for alkylsalicylate additives.