Abstract: The concentrates comprise specified proportions of diluent oil, an organic sulfur-containing antiwear and/or extreme pressure agent, an ashless dispersant, a dimethyl ester of an aliphatic phosphonic acid in which the aliphatic group has an average in the range of about 12 to about 24 carbon atoms, and a 3-hydrocarbyl-2,5-diketopyrrolidine in which the hydrocarbyl group is an alkyl or alkenyl group having an average in the range of about 12 to about 30 carbon atoms. By using weight ratios of diketopyrrolidine to the dimethyl phosphonate of at least 3:1, the concentrate remains homogeneous at temperatures at least as low as 12.degree. C. When utilized as a top treat in gear oils formulated with conventional GL-4 and GL-5 gear additive packages substantial improvements in limited slip axle performance can be realized.

Abstract: Gear oils and gear oil additive concentrates of enhanced positraction performance are described. They comprise: (i) at least one oil-soluble sulfur-containing extreme pressure or antiwear agent; (ii) at least one oil-soluble amine salt of a partial ester of an acid of phosphorus; and (iii) at least one oil-soluble succinimide of the formula ##STR1## where R.sub.1 is an alkyl or alkenyl group having an average of 8 to 50 carbon atoms, and each of R.sub.2, R.sub.3 and R.sub.4 is a hydrogen atom or an alkyl or alkenyl group having an average of up to about 4 carbon atoms. These compositions preferably contain one, more preferably two, and most preferably all three of the following additional components: (iv) at least one amine salt of a carboxylic acid; (v) at least one nitrogen-containing ashless dispersant; and (vi) at least one trihydrocarbyl ester of a pentavalent acid of phosphorus.

Abstract: Haze formation in additive concentrates containing boron-containing ashless dispersants is inhibited, and improvements in performance capabilities can be realized, by suitably controlling the pH of the concentrate as produced. Not only does such pH control result in no sacrifice in wear and corrosion inhibition, but it has been found possible by suitable adjustment and control of pH to actually improve the effectiveness of the concentrate in its ability to inhibit wear and corrosion. Moreover, such pH control makes possible the provision of compositions having enhanced extreme pressure properties as seen in the standard L-42 test, and improved antirust performance as seen in the standard L-33 test.

Abstract: Gear oil additive concentrates and lubricant compositions containing a combination of additives which minimize noise and vibration that occasionally develop in limited slip axles. The additive combinations include (i) an oil-soluble succinimide of the formula ##STR1## wherein R.sub.1 is alkyl or alkenyl having 8 to 50 carbon atoms, and R.sub.2, R.sub.3 and R.sub.4 are hydrogen atoms or alkyl or alkenyl groups having up to about 4 carbon atoms; and (ii) a boronated or non-boronated carboxylic derivative composition produced by reacting a substituted succinic acylating agent with (a) amine having at least one primary or secondary amino group in the molecule, or (b) at least one alcohol, or (c) a combination of (a) and (b). The substituent of the succinic acylating agent is derived from polyalkene having a number average molecular weight of about 500 to about 100,000. The additive concentrates and lubricant compositions are devoid of any metal-containing component.