Low-Ash Lubricating Oils For Diesel Engines

摘要

The lubricant for a sump-lubricated, compression-ignited engine may contain an amount of a C12-C24 carboxylic acid-based fuel additive or component obtained by migration from the fuel. Good lubricant performance is obtained by including in the lubricant a boron-containing additive in an amount to provide about 2 to about 500 ppm B to the lubricant, provided that the total sulfated ash level is less than 0.8 weight percent.

主权项

1. A method for lubricating a sump-lubricated, compression-ignited engine which is fueled by a liquid fuel containing fatty acid-based fuel additive or component, wherein said fatty acid-based fuel additive or component is susceptible to or does migrate into the lubricant in the sump of said engine, said method comprising supplying to said engine a lubricant which comprises:
(a) an oil of lubricating viscosity; (b) a boron-containing additive comprising a borated succinimide dispersant containing about 0.5 to about 5 weight percent boron (oil free basis), the boron-containing additive is about 0.1 to about 5 percent by weight, and in an amount to provide about 2 to about 500 ppm B to the lubricant; (c) an overbased detergent having a TBN (oil free basis) of at least 400; said lubricant having a total sulfated ash level of less than about 0.8 weight percent; and wherein a phosphorus content of the lubricant is less than about 0.12 percent by weight.