The only "Real" none conductive fluids are not with in the normal price range of any thing you would consider. We have some 3M product here but it will set you back between £45.00 to £125 Per Kilo (1/2 Ltr approx) depending on which one you would like. All so they are 4x heaver than water and all so require specialist equipment to run.
Thanks for that information. I will just have tou double check my fittings and make sure they don't leak before I instal/run the system.
How do you suggest I clean out the rads prior to instal? Is using tap water a bad idea, or should I just run clean distilled water only? How many litters should I run through it to be sure it is clean?