A marine diesel cylinder lubricant composition for a marine diesel engine running on fuel having a sulphur content of less than 1.5%, the composition having a total base number, as determined according to ASTM D2896, of more than 30 and less than 70, and comprising at least 40 wt % of an oil of lubricating viscosity, and at least one detergent prepared from at least two surfactants, one of which is a salicylate. The marine diesel cylinder lubricant composition demonstrates good ability to reduce deposit formation, especially on pistons. The marine diesel cylinder lubricant composition also demonstrates good lubrication at temperatures above 250° C.