I drained my dexcool coolant the other day, and refilled with Zerex 05.
To get to the engine drain plug, work your way around the exhaust manifold with a 13mm (?) socket drive. We've got to get the coolant out of there!
Also, pull out heater hose at the rear of the engine, closest to the firewall.

To refill, open up the bolt atop the engine head while pouring coolant to the reservoir. Watch out until coolant overflows on this bolt, then screw it back on. If you do this, you will not have any air pockets in the system.

I did not make this up it is in the MB procedure manual!

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joel

Prayers bring forth enlightenment.