hello mate thanks for getting back to me I've changed rad, bottle,water pump, cap,thermostat but would have thought if it was head gasket it wouldn't cool down so quick oil is ok no water no steam coming out the back

hello my R R does almost the same I've replaced everything ticks over no problem when I drive if I go over about 55/60 temp goes up to red if I back off again to 50/55 the temp goes straight back down to just over half way again any one had this before please