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 devoidd of any metal-containing component.