Reviving an old topic perhaps. I was having a discussion with some friends. We all swear by Mos2 and use it in our mowers, daily drives and sports cars. I personally have noticed an improvement in smoothness and fuel consumption by using mos2. Keen to hear everyones experiences. Anyhow, my friend's mechanic mentioned that Ceratec is better for alloy blocks, whilst mos2 is better for cast iron blocks? Is there any validity to this statement? For the record, I add half a bottle to my s2000 (but only when im not using a group IV oil) and half a bottle to my diamante (which uses conventional).