CPC C10L 10/04 (2013.01) [C10L 1/143 (2013.01); C10L 1/1616 (2013.01); C10L 1/196 (2013.01); C10L 10/06 (2013.01); C10L 2270/026 (2013.01)] | 14 Claims |
1. A method of reducing the incidence of deposits on the pistons of a 4-stroke marine diesel engine during operation of the engine when it is fuelled with a marine residual fuel meeting the ISO 8217 2017 fuel standard for marine residual fuels and having a sulphur content of more than 0.1% and less than 0.5% by mass, based on the mass of the fuel, the method comprising lubricating the engine using a lubricating oil composition comprising:
(a) at least 50% by mass, based on the mass of the composition, of an oil of lubricating viscosity;
(b) 5 to 25% by mass, based on the mass of the composition, of an oil-soluble or oil-dispersible alkali metal or alkaline earth metal salicylate detergent, or a mixture of two or more oil-soluble or oil-dispersible alkali metal or alkaline earth metal salicylate detergents, the or each oil-soluble or oil-dispersible alkali metal or alkaline earth metal salicylate detergent having a total base number of (TBN) as measured by ASTM D2896 of from 50 to 500 mg KOH/g;
(c) 0.1 to 10% by mass, based on the mass of the composition of one or more oil-soluble or oil-dispersible ashless dispersants; and optionally,
(d) 0.1 to 10% by mass, based on the mass of the composition of a polyalkylene-substituted succinic anhydride,
wherein the lubricating oil composition provides the engine with reduced asphaltene agglomeration and/or reduced deposits on piston and ring assemblies, as compared with a lubricating oil composition lacking component (c) and/or component (d).
|