Fed

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.

Fed.

Ford jeepman

There are a number of products which are said to flush the cooling system out, I know there is a genuine Ford treatment which is probably expensive but the other aftermarket suppliers offer similar products, nulon have one and I am sure Castrol have something as well, go to a big Autobarn as they would have a better range to choose from, any one else have ideas?
Cheers
Bill.