The coolant drain on the engine-block can be difficult to reach.

The plastic belly shield uses either a 8mm or 10mm socket/wrench to unscrew.

Be careful when tightening the radiator drain plug, if you tighten it too much the plastic screw will break.

I like to mix the coolant with distilled water.

I'm curious why the low level coolant light went on, on my W202 a faulty windshield level sensor could effect the coolant light.

Do a search for StarTuned Magazine and use the archive to read about coolant.