[quote="nelo"]
Hi X5d have done a few miles today just checked the water and have had to top up about 1 ltr only topped up a few days ago have read about the steel seal but would that do any good ?
only done 138K not overheating or any other problems cant see any water leaking from the expansion tank
so will have to see how it goes in the next few day
regards
lee

[/quote]
Im all in favour of short cuts and genuinelg hope it isnt the head gasket. Ut frankly given the temperatures, tolerances and pressures required to make a cylinder head in the first place, I really dont see how a magic potion in the radiator will suddenly repair or transform a knackered one.
Best bet is to keep going to try and trace the source of the loss then work out your options