When was the last time that your cooling system was drained, flushed and CLEANED with GM one part powered acid cooling system cleaner?
If anyone has ever dumped discount store antifreeze in a Dexcool cooling system it will plug it up and it will need to be cleaned.
We have no clue where anotherredman got her information but it is not correct. Your motor does have aluminum cylinder heads.
If your plastic pressurized coolant recovery bottle has ever lost coolant and allowed to go empty, Air in a Dexcool system will cause it to plug-up and the system will need to be cleaned.
Have an inexpensive *cooling system pressure test done which will find any external or internal cooling system leaks.
I believe that motor is a North Star motor if that's the case that motor if they over heat one time this now becomes a on going problem I would suggest changing all thermostat water pump coolant temp switch because with that being an aluminum motor the heads deform quickly witch in that case you would need to get the block resurfaced and a set of new heads for this car on top of head bolts and a head gasket set to fix the issue really sorry that's just bad news I see it all the time but hope changing the component to the cooling system will fix the problem but at least now you don't have that shock when the worst might happen
The bad news is that the non Northstar engine is famous for blowing head gaskets due to the aluminum block with iron heads and floating cylinder liners. The good news is that the Northstar engine is known for the same thing. Better get it to a garage or you will be replacing the motor or the car soon.
How unfortunate, you'd better fix it. Had you actually included any information other than the fact that it's overheating it may have been possible to suggest why it's doing this.
