A few of us 2004/5 owners have experienced fractured coolant tank s on the return pipe entrance to the tank. Tiny cracks appear causing the coolant/water to dribble out very slowly which over time can drop your coolant level quite dramatically if un-noticed. The tank also becomes very brittle.
Bad news is that a replacemnent part is �135 + fitting. The good news is that I’m in contact with Wayne at Sinclaires who is going to speak with ProAlloy about making an Aluminium tank for us who want a bit of bling.
If you find any small amount of coolant residue on the side of the tank then you should get it replaced asap.