Been having trouble starting my car for a while now when cold. The last cold morning I thought my battery was going to give up before it just started. The next morning I sat an electric fan heater in the engine bay an hour befor going to work. Replaced all four glow plugs yesterday and although it hasn't been cold I can tell the major difference when starting. My glow plugs had worn out about 5mm in length compared to the new ones. Easy job should have replaced them last winter. Car has done 315000 klms so should be right for another few years. Have a good day. Craig.