Rebe,

Yes it is overlooked, but what is really overlooked is the use of TAP WATER instead of Distilled water! The use of tap water is so much an issue with today's American Cars as the most Americans are used to the old cast-iron engine blocks that are bulletproof to tap water. Foreign car drivers are more educated on the use of the appropriate water, but the mistake for the all aluminum, or aluminum head engine will probably have premature "head gasket" problems as the result of aluminum corrosion with tap water.

No tap water...

Now, one Mercedes model (I know of) that has an inherent flaw when coolant is overlooked(the whole cooling/heating system even with the correct coolant, and correct water) is the W140. A plastic heater tee that is on the engine fire wall will fail around 100k Miles, and when it fails one has seconds before the engine is ruined for ever, so the overlooking of the cooling system is critical on the W140.

I guess nearly every car manufacture recommends the coolant cap be replaced at every coolant change.

Martin