Get an aftermarket gauge that actually indicates a temperature figure, then you’ll see it move up and down. Factory temp gauges are built to stay steady within certain parameters to keep the consumer happy. Once that needle heads north it’s already too late!!
The NA Loyales came out with a single core radiator. I’m not sure of what models came with dual core. Even here in Oz they all had single core for NA from factory.
If your AC gets warm at the lights it needs a service - or the fans looked at to ensure proper air flow when stationary.
Cheers
Bennie