| abstract |
The invention concerns a lubricant for a two-stroke slow speed crosshead marine engine, powered with a fuel with sulfur content not less than 1%, consisting of a mixture of distillates used as lubricating bases containing x wt. % of dispersing additive of the succinimide type, y wt. % of an overbased detergent additive of the sulfonate type, and z wt. % of an overbased detergent additive of the phenate type. The invention is characterized in that x, y and z are selected in the intervals 0.5<=x<=2.5, 2.5<=y<=10 and 11<=z<=24.5 such that 15<=x+y+z<=36 and 1.5<=y/x<=13, the BN of the lubricant, determined according to the ASTM D-2896 standard, is not less than 70 mg KOH/g, and the speed at which sulfuric acid is neutralized by the lubricant, defined by the maximum speed of pressure increase of a closed chamber, with its walls covered with a film of said lubricant from 80 to 100 mum thick, maintained at 100° C., wherein is introduced a known amount of sulfuric acid, has a value not less than 11x102 Pa/s at 100° C. |