Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
What model is your chevy?
How far back is the puddle on the passenger side? Near the engine or under the passenger seat?
Do you see any fluid inside the vehicle?
On the passenger side of the engine the parts that can leak coolant are the heater hoses and a freeze plug.
Heater hoses will occasionally rupture and leak right near the firewall.
Freeze plugs are not nearly as likely to leak, but it's possible. They usually only corrode through if there has been very little coolant and too much water used in the cooling system.
Have you attempted to add coolant to the system to see if it runs back out somewhere?
For the most part they are all the same or very similar these days. Your vehicle should use a DEXCOOL compatible coolant, but really any long life universal coolant will work. There's no need to pay extra for the fancy DEXCOOL brand name.
Please let me know if you need additional info.
I'd be happy to help identify the leaking part if you are able to see where it seems to be coming from after you add to it.