Check the level in the expansion tank when cold. The one on my 2002 Plus8 had a tab inside to indicate the cold level. It was at about 50% full level.
The rad top filler cap was useful when filling up during a coolant change. It helped get rid of air and final topping up.
No coolant losses over 10+ years of ownership and just occasional very small top ups to the expansion tank. In my view the aluminium Morgan rad that a previous owner had fitted ( possibly a replacement based on dates in the file with the car)is slightly under capacity for cooling. It was very sensitive to airflow through the core and the fan cut in during slow/static driving. Never overheated, just the fan noise!
