for my vz v6 alloytech motor should i use tap water or deionised water?
You can use whatever you like. There are no laws or restrictions on what to use.
I only use demineralised water in my cooling system.
The Blue One
technically you should use distilled water or pure water as the minerals in tap water can lead to corrosion.
LOL, no laws about what water to use..
Cop pulls you over, "Hi mate, just wanted to see if I could check your radiator please"
You, "How come?"
Cop, "I need to make sure your not running any tap water in there, it's against the law!"