in the HR31 skylines, they have a single core radiator.
in the australian delivered they have double core radiator the same size.
all the imports like r32s silvias etc have pissy little radiators.
My point being they were not intended for Australian conditions. They have to be in tip top shape to handle 40+ days, i.e. good working pump, no leaks, working thermostat. That said, it should be common practise for any car of age.
i went to the Just Jap Cooling Pro radiator, and noticed a 4-8 degree drop on an average drive, today was 40 degrees and the temp was sitting on 80degrees the whole 30min drive home from work. that rox the sox of any other car ive owned, turbo & non turbo