>| I use NGK plugs in all my equipment.  My experiance with Bosch is that when
>| they start to get old, they go bad very rapidly. The NGK seem to have the
>| same level of performance  right through the time that I replace them.

        I had a NGK plug shear at the top of the threads on my Golf...
Went to change them out because I had lost spark in one cylinder about half
the time (center electrode on all 4 plugs were worn to a pin thin triangle).
I got 30K out of them which was from the time I bought the car used. Thus,
I don't know how long they actually were in the car - just know that
the one got stuck and we broke two Craftsman sockets trying to remove the
threads with an easy out...

dave