My RX-8 is dumping coolant
 

After an unfortunate incident involving a broken serpentine belt to the water pump and an overheated engine, I trailered my 8 home expecting a dead engine. Just for closure, I bought some coolant from the dealer and filled the system back up, just to see the engine run perfectly. I watched the temp off OBD, and it looked like the thermostat was working fine, and there wasn't any coolant obviously on the dipstick. So i drove it for a week to class and back, and one day handed the keys to my dad to test, and he drove to Detroit and back without any issues. Then, the next day when I was going home from class, i stopped to get some gas and smelled coolant. It looked like the car dumped coolant from the overflow tank's hose. So I drove it home without the temp gauge moving at all, and parked the car. My guess was the water that probably wasn't supposed to be added in was boiling over, so I drained the car of coolant and replaced it with pure Mazda-branded FL22 I bought from a Ford dealer. I also bought a new radiator cap just to make sure. I took it for a test drive to McDonald's, and when I looked under the car it was dumping coolant all over the ground in the old position, and also on the other side as well. I'm honestly at a loss on what to do outside of replacing the entire cooling system, and if that doesn't work the engine. Any suggestions will help a lot.

Thanks!

Edit: I also think it's worth mentioning that the coolant only leaks when the car has been driven. I have had it idling and not leaking at all for about 30 minutes before I decided that nothing was going to happen.

You need to get your cooling system flushed and pressure tested to find out where it's coming from.

Can you see where it is coming from?

There is a nipple under the coolant overflow bottle that tends to break off the radiator

The overflow bottle or a coolant line could be leaking or blown off as well.

If it is only leaking after it warms up you should look at the radiator side of the system...there isn;t much flow there until the thermostat is open

It doesn't leak when the car warms up and the thermostat opens, as I let the car run for 30 minutes and watched the temperature drop on OBD. It only seems to dump coolant when I actually drive the car.

Alright, i found the source of the leak. there seems to be a hole on the plastic bit of the radiator. I have no idea why it wasn't leaking at idle. Thanks guys!

Is it on the top plastic tank of the radiator? Could be the coolant overflow hose nipple.