An idiot asks.......

so on the subject then what's the difference between the cheap blue stuff in halfrauds and the like and the expensive red stuff from the same places? I thought it was purely about concentration of active ingredients and have mixed them in the past with no dire consequences (not in the landrover before anyone mentions my recent cooling problems) but perhaps I am wrong...

Given the choice it seems obvious that if you've bought one sort, it might be worth just draining the system of the other sort and refilling with just one sort? s'what I'd do anyway, and I'm feckin' skint.

Not worth trying to save a few quid on, and for the issues that can result seems to be money and time well-spent as insurance if nothing else!