What's best to use ? Tried some rad cleaner from Rover (supposedly the stuff
they use in workshop) and it was absolute carp.

Read on a thread recently about dish washer tabs, what's the verdict ?

Nige

forte do a bio degreaser for about a fiver which smells of oranges and works well , leave it in for a few hours and it does emulsify all the oil and leaves the header tank looking very clean HTH

Just checked their website, looks like the stuff I need....Now where to get it ....
Ta Froggy