Here's one for the engine experts --- Never having owned a diesel car before I wondered about the merits of using a fuel additive like Redex in the fuel system, is it beneficial for a diesel engine, especially a brand new one, and will it affect the warranty??? I have used Redex occasionally in all my previous petrol engined cars and never had a minutes bother with the fuel system on any of them so I assume it works to some degree. I have heard horror stories about how the increasing amount of Bio fuel content in fuel, especially supermarket fuel, can adversely affect some engines. Any advice?????