| 摘要 |
An additive concentrate preferably having a TBN greater than 300 suitable for incorporation in a finished lubricating oil composition, the additive concentrate comprising (a) a lubricating oil, and (b) a lubricating oil soluble detergent which is an overbased metal salt obtained by an overbasing process including a carbonation step and modified by reaction to incorporate from greater than 2 to less than 40% by weight based on the weight of the concentrate of either (i) at least one carboxylic acid having the formula (I): <IMAGE> (I) wherein R is a C10 to C24 alkyl or alkenyl group and R1 is hydrogen, a C1 to C4 alkyl group or a -CH2-COOH group, or an anhydride or an ester derivative thereof, or (ii) a di- or polycarboxylic acid containing from 36 to 100 carbon atoms or an anhydride or an ester thereof, and further modified to incorporate by addition prior to carbonation a hindered phenol or naphthol having antioxidant activity.
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