I was thinking they were TX3. Always found it strange that Ford went from Ghia models having alloys in the KB, to metallic hubcaps in the KC, and plain plastic in the KE.
But then again, Holden did the same thing with the astra - the SLE ended up with SLX hubcaps.
With regards to warm up, I just meant driving. I presume you start it, and wait 10 to 30 seconds before it goes in gear (ie don't put it in gear until the revs drop from the initial flare).
Five mins sounds fine - quite reasonable actually.
And remember, don't pull the plug out of a hot engine - those 80s alloys love stripping threads. Wait for it to fully cool. Basically, if it idles fine, we are trying to see the colour at regular driving. If you idle it more than a minute after driving, the colour may change a bit. No problem in regular use, but when you are trying to see the plug colour, it will change it.
