Why would you even consider removing the head when you have no problem? All you have is a concern, and perhaps misplaced. When it starts boiling over and you see a thick brown mousse floating in the coolant, then you have a problem. Until then, just keep driving and be happy your engine runs strong. If it stays under 120 C on the dash gage, you shouldn't be concerned about engine damage.

Re your title, "low on pollution?", you live in CA so can buy Propel's Diesel HPR which is made from bio sources. Thus, it is adds no net CO2 to the atmosphere. That makes you better than all-electric cars from the "climate change" perspective, which is the current main environmental concern. NOx is no longer much of a problem, even in the LA Basin where one can now see the snow-covered mountains from the beach, at least on clear winter days.

__________________
1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans