As per title , when I bought the car there was no pinking at all and on collecting it put £25 of unleaded in from a Shell petrol staion. After that had gone filled it right up from another petrol station in my area Harvest fuels station (only one I have ever seen ) and since then its started to pink under load,not all the time mainly when very hot like today. The cambelt was changed last weekend so the timing is bang on.It seems to have started since filling it right up with fuel .To me this says its the fuel causing the problem.Anybody got any helpful advice on this .