[quote="ken"]...someone who feels the need to changes their undercrackers 10 times a day on the basis that they might just be struck by a bus or a meteorite ?

ken.

Good analogy probably not too far from the mark. I like!
Nobody here has as yet suggested a magnetic dooverlacky incorporated in the drain plug?
Works a treat on my 1909 gear cruncher Sizaire.

That's 'cos Citroen had already thought of it.

The volume of 'whiskers' on the magnet makes it easy to spot those customers whose driving style regularly defeats the synchromesh...

ken