Lou,

I think what Quasimodo is saying is that if you mix 200ml of Castor with 300ml of Ether the total does not equal 500ml of mixture. This is a fairly standard mix for ball raced diesels (add 500ml of Kero and you've got Olly Brew).

The fact that some apparently dissolves does not in anyway reduce the effectiveness of this brew. Most competition modellers using TBR Iron/steel motors will use this or a very similar mix. And as far as I know will mix by volume not weight.

I've actually been putting off making up some diesel fuel, but when I do it'll be Olly brew, with 1.4% Amsoil added after the full litre of fuel is mixed. This method is again pretty standard for competition modellers and produces repeatable results with a minimum of pfaffing about and having to do complicated maths. (like what's 100% - 1.4% );-)