I just finished doing a head gasket on my EF but I still have some leftover oil in the water system and a yukky plastic reservoir.
At the moment I'm using straight water and I'm looking for something to add to the water to clean out all traces of oil before adding fresh coolant.
Dishwashing liquid? Degreaser?
The old oil seems to stick to everything & naturally won't mix with the water.
BTW, you guys have a top site here.