Theres also a coolant test....
That uses some "Blue" Chemical that has a bobber that breathes the odors in your coolant to see if infact you have a bad head or head gasket.

Generally,
Head gaskets or the head dont have cracks in them..It usually turns out to be the LIM Gasket. seeping..

I have changed both the upper and lowers and and have choosen to no longer use "DEXCOOL"...

I have been useing the all blend 50/50 from Oreilys. Since haveing done that.. My Motor now once again runs as cool as it did when it was new 14 yrs ago!...(Currently at 165,000 miles) To my amazement...I also gained fuel mileage!...
Yes I did instahl a new radiator, Since the DEXCOOL sludge attack...
Just to eliminate any mixing/sludge clogging issues.. Incase it had any residual remnants left in the system...

I believe anti-freeze life span is like 5 yrs.. after that it tapers off quickly...(as far as its effectiveness) I choose to change mine out every 2 yrs since the sludge incident.
I also do my oil changes every 3 months 3000 miles faithfully.
Maintenance is key obviously...
Since I have maintained mine since it was new...My maintenance is a no brainer...
I believe a lot of issues also arise due to past ownerships..
Meaning if you bought yours used for instance...
Who knows...how well it may or maynot have been maintained...
I think thats why it pays to be a Bit **** about your maintenence schedule.. If your plans are to keep it in tip top shape and want it to last for many years to come!

 

I go back to "follow the instructions on the bottle". Each manufacturer has slightly different instructions. I think one says to drop it on the car and run it for a week, another 15 minutes. Just follow what the bottle says to do.

 

well i know the full history of the car my uncle is the original owner and it has had major oil leaks in the past and most if not all are not original gaskets for prone oil leaking spots. now my mechanic most likely might have used dexcool it was originally orange, he is a GM Specialist not dealership affiliated tho. my hunch is on rust in the system has majorly contaminated it now so im deemimg a flush a necesity. last summer the radiator did come out to change my condensor not sure what he did with withh the coolant at that point. until it overheats or has any problems im assuming it just needs a flush and fill

 

How do I know when to change coolant? If it is in my 1996 Impala SS, when I see all the water and coolant in my driveway after leaking out. If this car isn't leaking oil, it's leaking water. Never ends...