Cleaning oil from cooling system?

Hi
I am in the middle of changing the head on my Disco 300tdi after the previous head was cooked. The problem left me with no option but to install a new cylinder head (the old one had previously been skimmed down a couple of times).
During the work I am seeing lots of oil deposits in the water system from the previous fault. What would be the best way to flush/clean this out? There is no hose near where I am working on the vehicle. It has been suggested to me that I put some sort of detergent into the system and run it for a couple of days, then drain the water and refill the system!

thanks

dishwasher LIQUID

Or dissolved dishwasher powder or automatic washing machine powder.

You can buy some commercially available cooling system cleaners, but dishwasher stuff works just as well. Don't try putting a tablet in!!! I know someone who has

be very careful with powders - they can clog radiator matrices - hence why I said liquid!

Thanks for your help, everyone. I'll get some liquid when I finish putting the head back.