Thanks you Guys. Roger, is Millers a similar product to 'Water Wetter' which I know a lot of people use with success. My critics of LI 115 say that it might be ok in a vintage car with a relatively slow revving engine...Mr Jay Leno for one, but not in a high performance machine like our 150 hp Mini. The cruisers that oldfart mentions fall into this catergory. I had a suspicion that the engine bores in particular might get hotter with LI 115 but that would be offset by an increase in boiling point as Roger has pointed out. The product has a very definite oily feel about it which would slow down its passage round the cooling system which I think is a good thing. Am slowing down my water pump speed with a bigger pulley as I am sure that at 8000revs it is just cavitating, which is why a lot of Mini racers use electric water pumps that run at a constant speed. This is fascinating and it is a problem that a lot of race cars have, so keep the ideas coming, I appreciate it.