LUBRICATING COMPOSITION FOR FOUR STROKE ENGINE WITH LOW ASH CONTENT

摘要

The invention relates to a lubricating composition for a four-stroke engine with a low ash content, that comprises : a) one or more base oils selected from oils of groups I to V, preferably from oils of groups III or FV of the API classification; b) at least one compound (b) selected from the group of heavy PAO with a kinematic viscosity at 100°C of between 75 and 3000 est, optionally mixed with one or more compounds selected in the group of polymer compounds of the polyisobutene (PIB) type or a mixture thereof; and c) at least one ester of the formula R(OH)m, (COOR' (OH)p)n in which m is an integer from 0 to 8, preferably from 1 to 4, n is an integer from 1 to 8, preferably from 1 to 4, and p is an integer from 0 to 8, preferably from 1 to 4, wherein the sum p+m is strictly higher than zero, R and R' independently represent a linear or branched, saturated or unsaturated hydrocarbon group optionally substituted by one or more aromatic groups and including from 1 to 30 carbon atoms, or the borate derivatives thereof; wherein said composition has a sulphated ash content lower than or equal 0.5% as measured according to the ASTM D874 standard, a phosphorus content lower than or equal to 500 ppm as measured according to the ASTM D5185 standard, and a sulphur content lower than 0.2% as measured according to the ASTM D5185 standard. The composition has good detergency properties, and the use thereof enhances fuel savings.