Lubricating oil additives

A lubricating oil composition comprising at least 50 percent by mass, based on the mass of the composition of an oil of lubricating viscosity and 0.01 to 25 percent by mass, based on the Mass of the composition of an oil-soluble poly(2-oxazine) polymer having the repeat unit:

• where the number (n) of repeat units is an integer between 4 and 500;
• wherein the polymer carries an inorganic or organic nucleophilic polymerisation terminating group (t), and an initiator group (i) connected to the N atom of a repeat unit, the initiator group (i) being effective to initiate the polymerisation of linear, branched or cyclic hydrocarbyl moieties;
• and
• wherein each R1 independently comprises a branched or cyclic hydrocarbyl groups having 1-50 carbon atoms, or a macro-monomeric hydrocarbyl group with more than 50 carbon atoms;
• with the proviso that when R1 comprises linear, branched or cyclic hydrocarbyl groups having 1-50 carbon atoms, the R1 of at least one repeat unit is a linear, branched or cyclic hydrocarbyl groups having 12-50 carbon atoms.