Wollfen
Old Man with a Hat
here is a radiator cap with a temperature gauge in the top. I think that could be useful for some people when troubleshooting on the road.
Car 1.1 Bar Thermostatic Radiator Cap 16 PSI Pressure Rating Temperature Gauge | eBay
Car 1.1 Bar Thermostatic Radiator Cap 16 PSI Pressure Rating Temperature Gauge | eBay