A new aluminium alloy containing (in wt.%): 0.2 - 0.5 Fe; 0.7 - 1.2 Si; 1.2 - 1.6 Mn; up to 0.3 Mg; up to 0.5 Cu; up to 0.2 Zn; up to 0.1 Ti is used to make the fins of heat exchangers particularly car radiators. The finstock has high post braze strength and thermal conductivity, and has a sufficiently electronegative potential as to be capable of acting as a sacrificial anode for the heat exchanger tubes. By virtue of the absence of Sn, In and Cr, these heat exchangers can be scrapped and melted for re-use.