Folk who drive around in old old cars will be familiar with the occasional need to do something a bit proactive for the car's welfare. My parents recalled the traditional ritual of radiators boiling over on Shap Fell, before the M6 tamed that bit of Cumbria; for my part, no summer would be complete without our having chugged up Telegraph Hill on the A38 west of Exeter, at about 15 MPH, with a queue of frustrated motorists behind, all the windows open and the heater going full blast to try to keep the water temperature down.
I've been watching the temperature gauge closely for ages; I replaced the radiator four years ago, after some serious overheating resulted in a cracked cylinder head; everything was running fine until a few months back, and then I started to see the operational temperature creeping slowly upward. And this hot weather pushed it up beyond 90C the other day; and it's a real bind driving around with the heater on in a heatwave.
So I took the radiator out and backflushed it, and shook all the loose bits of matrix out, and hoovered the whole damn thing, and stuck it back.
Situation improved, but I may install a summer thermostat; a 74C one arrived in the post yesterday....