Which coolant is more suitable for Xtool P2S?

Assuming the P2S is similar to the P2 (which from what I have seen it is) the laser should come with a bottle of coolant mixture.

This is what I have used and its performed without issues. Unless you have a reason to go with something else, I would use whats included with the machine.

I have not heard of anyone hooking up an external chiller to the P2 line since its all internal.