"Pete L" wrote:
I re-sited a radiator which now drips. I put plenty of PTFE tape on,
made sure olives were ok and tightened as much as I dared - but still a
slight drip from each side around the valve. Now the weather has turned
colder and the heating comes on there is no drip. I guess that
expansion is the reason. Now the radiator is dry and warm would anybody
recommend putting some sealant around the joints?

I would apply plumbers jointing paste (boss) to the threads:
http://www.diytools.co.uk/product.as.../3428!TB_MISBW
PTFE tape isn't much good in these circumstance, and applying sealant around
the joints externally is useless.