Use of lubricating oil compositions.

摘要

Use of a lubricating oil composition as an inlet-valve deposit inhibitor characterised in that the lubricating oil comprises a polyether of the formula RX[(CxH2xO)n(CyH2yO)pH]m wherein R is either an alkyl or alkylphenyl group having from 7 to 30 carbon atoms, X is selected from 0,S or N, or RX together represent H, x is an integer from 2 to 4, y is an integer from 6 to 30, m is 1 when X is O or S or when RX together represents H, or m is 2 when x is N, and n and p are such that the polyether contains between 0 and 40% by weight of (CyH2yO) units and between 35 and 80% by weight of (CxH2xO) units is disclosed. In particular, it is preferred to use a lubricating oil composition consisting essentially of the polyether, a synthetic lubricating oil and optionally a mineral oil. In the preferred polyethers, the (CxH2xO) units comprise at least 50 mol % of oxypropylene units, preferably 100 mol %. Preferred synthetic lubricating oils are polyalphaolefins and polyol esters.