Thanks for all that help.
Do you guys think that, given the symptoms my car shows, the thermostat may be bad (or at least not-so-good)?
I recall that it runs fine at 80deg when at speed, at about 100deg when stopped and sometimes up to almost 110deg. If the thermostat was bad, I suppose that it couldn't be cool even when running, true? It sounds to me more a low water cooling capability or radiator efficiency matter.
Please illustrate me as I am not very familiar with the cooling system.

Best regards