Just to add a little bit to this (rather old) discussion, I'm in the process right now of changing out the coolant in my Caliber, and maybe some of the things I found will help others.
Regarding the radiator drain plug: while it's possible to reach the drain plug through the opening in the plastic shroud underneath it, it's nearly impossible to manipulate the plug itself. That being the case, you really should take the front fascia off the car...it makes accessing the plug a LOT easier, plus you can check out the state of your radiator and brush away any debris that may have accumulated.
The black plastic lip underneath the bumper, which is also a plastic shroud that extends under the car, is RIVETED to the bumper, and cannot be removed by itself. The whole fascia must come off. It sounds difficult, but is actually quite easy.
First, if you have fog lamps, reach up through the hole in the black plastic shroud underneath each and disconnect the electrical connector for each. Press in the tab on the connector, and it just pulls right off.
To remove the front fascia, you will need to remove:
- three 10mm bolts from underneath the black plastic shroud, in the center of the shroud
- four plastic plugs underneath the black plastic shroud, two on each end where it meets the splash guards near each front wheel. Pry up the plastic center piece with a flat-bladed screwdriver until it starts coming out, then use a pickle fork or a pair of wire cutters (carefully!) to pull the center piece all the way out. The rest of the plug then pulls out easily.
- the front section of each front wheel well splash guard must be pulled back to reveal a hidden bolt. To do so, remove the two 7mm screws you'll find along the front edge of the wheel well (where the painted bumper meets the splash guard), then remove the single plastic plug towards the engine side of the splash guard. Pull back the splash guard.
- You'll find a 7mm bolt that attaches the edge of the bumper (right where it ends at the wheel well) to the front fender. Remove these screws.
- Six T-20 screws along the upper edge of the fascia near the front of the hood.
At this point the fascia can be removed. Pull the sides of the bumper outwards (so they clear a plastic tab that helps hold them up), then pull the fascia straight off the car.
Now it's VERY easy to get to the drain plug. It's not threaded...turn it about half a turn counter-clockwise and the coolant starts to flow. BE CAREFUL...if you turn the plug too far counter-clockwise or pull on it too hard, it will come completely out of the radiator!
It's also possible to remove the lower radiator hose to drain the coolant, but I found that I needed to remove the battery and battery tray to get at the clamp. This is not difficult either, but it doesn't get quite as much coolant out of the car as the radiator drain plug since it doesn't connect at the very bottom of the radiator, but about 1/3 of the way up. To remove the battery, first disconnect the negative, THEN the positive leads, using a 10mm socket. Down at the bottom of the battery near the front is a 13mm bolt that secures a beefy plastic tab that holds the battery in place. Carefully loosen this bolt (hit it with PB Blaster to loosen it up if necessary) so there's enough play in the plastic locking tab to remove the battery. Remove battery. Remove the four 13mm bolts and the 13mm nut holding the tray in place, then lift it out. The hose clamp can then easily be reached, and you can also easily aim the hose towards your drain pan.
The 2.0L engine has a 7.2 quart capacity. I found that about half of that comes out when you drain the radiator and the overflow tank. As such, I'd suggest draining the car, filling with DISTILLED water, running it up to temperature, draining that out (after it has cooled down!), and repeating the process until the distilled water comes out clear (or mostly clear). At that point, do a final draining of the system, then pour in exactly half of the capacity (which in my case is 3.6 quarts) of UNDILUTED G-05 coolant. Zerex sells a G-05 coolant in both undiluted and pre-diluted forms, so be sure to get the right one! Top off the car with distilled water, and you'll have the 50/50 mix of coolant and water that you need. Burp the car as necessary (raising the front of the car helps get all the air out), put the car back together, and you're good to go.
