The present invention provides a non-aqueous lubricant composition comprising a base stock and 5 at least 0.02 wt % of a friction reducing additive which comprises a block co-polymer of at least one block A which is an oligo- or polyester residue of a hydroxycarboxylic acid and at least one block B which is a residue of a polyalkylene glycol. The invention also provides the use of a block co-polymer of at least one block A which is an oligo- or polyester residue of a hydroxycarboxylic acid and at least one block B which is a residue of a polyalkylene glycol to reduce the kinetic co-efficient 10 of friction in a non-aqueous lubricant composition when compared to an equivalent lubricant composition comprising no block co-polymer.