Abstract: 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): ##STR1## wherein R is a C.sub.10 to C.sub.24 alkyl or alkenyl group and R.sup.1 is hydrogen, a C.sub.1 to C.sub.4 alkyl group or a --CH.sub.2 --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.

Abstract: An overbased metal salt of a hydrocarbyl-substituted sulphurised or non-sulphurised phenol, a calixarene having a substituent hydroxyl group or groups available for reaction with metal base or a linear phenol/formaldehyde resin wherein the metal moiety comprises a first metallic component which is at least one alkaline earth metal and a second metallic component which is at least one of either (i) at least one alkali metal or (ii) at least one metal selected from Groups IIIa, IVa, Va, VIa, VIIa and VIII of either the first or the second transition series of the Periodic Table of the Elements, the weight ratio of the first metal component to the second metal component being in the range from 1000:1 to 2:1.

Abstract: The detergent inhibitor package has been found to influence the viscometric properties of SAE 5W lubricants that have less than 5 mass % of non-conventional basestock, use a basestock that has an average base stock neutral number not less than 105, a calibrated Noack volatility of not more than 22 wt. % loss, and a kinematic viscosity at 100.degree. C. (kV 100, measured by ASTM D445) less than 12.5 cSt. In particular, neutral and overbased calcium salts of organic acids have been found to increase low temperature high shear viscosity when measured in the CCS (ASTM D5293). These salts which are widely used for their detergency and acid neutralization properties should be avoided altogether or used at a level not exceeding 0.0007 moles of organic calcium salt per 100 grams of lubricant. Where diesel performance is required, for example to lubricate passenger car diesel engines, a calcium salt of an organic acid may be required to control piston deposits.