Engine coolant replacement

[Zundels]

Getting the R-25 and the Cummins 150 engine ready for spring launch, I see in the manual that it is recommend to replace the engine coolant every two years. Some TugNutr's even suggest changing once a year.
If any of you have replaced your Cummins closed engine coolant, we need your assistance.
Looking at the manual the drain plug is on the port side of the engine behind the WIF fuel filter. I found the drain plug and it is nearly impossible to get a wrench on the head of the drain plug, with other components in the way.
What is the best way to drain or replace the coolant?
Can we just pump out the storage container from under the cabin step?
We could use step by step instructions... what tool worked, things to look out for (dropped tools in the bilge) etc.

Thanks, Don

 

[Zundels]

Andrew suggests that for our 2009 R-25 classic we need to use Fleetguard ES Compleat to replace the coolant, and that we contact Cummins NW for more details to remove the drain plug. Will update as more is known.