Abstract: A liquid lubricant base oil composition comprising (i) a base stock comprising at least 95% by weight saturated hydrocarbons such as for example a Group II base stock, a Group III base stock and/or a base stock derived from Fischer-Tropsch synthesised, waxy, paraffinic hydrocarbon material and (ii) 0.2 to 30% by weight of an aromatic extract which has a dimethyl sulphoxide extractable polycyclic aromatics content of less than 3 weight % may be made by blending the components together and may be used with one or more additives in a lubricant composition which may be used in applications such as marine engine lubricants.

Abstract: A method of lubricating a two-stroke, diesel crosshead engine comprises lubricating the engine with a cylinder oil and with a system oil, which oils are different from each other, in which the system oil is an SAE 20 or SAE 30 oil, has a total base number of at least 10 mg KOH/g and comprises: (a) a base oil; (b) at least one detergent additive in a total amount of detergent corresponding in performance, as measured by the Hot Filtration Test, to at least 1.5% by weight of the system oil, of a calcium alkyl salicylate detergent soap in which the alkyl group is a C12 to C30 alkyl group; and (c) at least one anti-wear additive. The method further comprising replenishing the system oil in the engine with a top-up system oil, in which the top-up system oil has the same additives as in the system oil previously charged to the engine but has a viscosity which is lower than that of the system oil previously charged to the engine.