Coolant type?

You are okay to use that kind of coolant here is a guide to help you flush the system and refill it with DEXcool. Here is what the book says.

https://www.2carpros.com/articles/coolant-flush-and-refill-all-cars

ENGINE COOLANT
A 50/50 mixture of clean water (preferably distilled) and use only GM Goodwrench(R) DEX-COOL(R) or Havoline(R) DEX-COOL(R) (orange-colored, silicate-free) coolant, or an approved recycled coolant conforming to GM Specification 6038-M (GM P/N 1052103).

Please let us know if you need anything else to get the problem fixed.

If you mix them and they are not compatible, you will know very quickly.

Do not mix Dex-Cool or HOAT coolant.

Drain and flush cooling system, use recommended coolant.

The green stuff by Prestone 50/50

You need to see if the supposed 100K mile type of antifreeze is in it. No matter what kind, I prefer Prestone, but Peak is also very good.

It sort of means use Dexcool and nothing else!

The Medic

It may be possible. I ran into this one time. The person flushed there system and put the regular Green anti-freeze in it. The vehicle started overheating, they changed the thermostat and radiator. Still overheated they called me and I checked the system ran vehicle to see if the was a possibility of an air pocket that was causing the over heating so I then reflushed system and put correct anti-freeze in it and no more overheating.

I would suggest you jack up vehicle run vehicle for a while and then turn vehicle off let cool check coolant if low fill and see what happens. Just don't let vehicle overheat to point of possible damage.

Jacking up vehicle will help any air pockets to work to the top or highest point of engine