It's ironic but some have found after an all aluminium larger capacity radiator upgrade that the car runs hotter in certain circumstances typically motorway cruising I believe. Reason is the thermostat which remains partially closed for longer to compensate for overcooling. It messes up the hysteresis but a thermostat change solves I understand.
Yes, thermostat change helps, but it needs a second component. I had to partially cover the efficient aluminum radiator so that its effectiveness is about equal to the effectiveness of the weaker OEM radiator. Ford calculates the radiator efficiency quite accurately because it is part of the overall working system. I don't know if the Plus 4 has a comparable cooling system, but I assume so.
