Ac Delco coolant is General Motors dexcool (it will read something like GM spec 6277M) - its a pretty nice OAT coolant provided your system is not leaking anywhere. On a clean system it will work for 150,000 kms without issue and your engine will look brand new shiny internally when you change the coolant at 150,000 kms. - I just changed coolant on a mazda 6 (first models built in USA were filled with dexcool), the system was shiny clean as if it were brand new.
It is perfectly fine for aluminium engines and aluminium/plastic radiator/heater systems.
If you google dexcool - you will find a million pictures of clogged systems, those are not the fault of the coolant but leaking cooling systems which can cause air leaks into it. (Old GM radiator caps had cork seals on them which would leak when old) The air in the cooling system will congeal the coolant at some places. Make sure the system is 100% airtight and burp it properly.
Dexcool should smell like concentrated rooh afza and be either orange or reddish pink.
Your vitz should have the pink coolant in it, you dont need to change/service it at any time before 200,000 kms. Did you lose your original coolant?