[Bobalong]

Talking to my mechanic the other day and in a casual conversation asked him
" How hot can an engine get before it becomes an issue?"

He his response was that most electric cooling fans in cars come on right at 130 deg. So probably 140 is the limit before it gets serious.

I get puckered when my 400 engine gauge hits 125 -130 with A/C on at a traffic light in the summer. Not sure when the dash light is supposed to come on but it never has after start up.

When these cars were new, many never had gauges, only idiot lights, wonder how many 140+ deg engines were just driven as long as the light never came on, or just as long as it went off after traffic started to move and some air went across the radiator.

Oil quality has improved dramatically since the 70's, Maybe this temp issue has been overrated and promoted by the industry manufacturing aftermarket fans, radiators, and magic potions to add to the coolant.

Just food for thought.
I'm still running a GM flex fan 4 core radiator and off the shelf anti freeze. All the factory shields and things to direct the air thru the radiator are in place.

Just my 2 cents, results may vary, proceed at your own discretion,