On Sun, 13 Mar 2005 05:58:10 -0500, "HarryS" >
wrote:

>I buy the OEM Champion the cheapest plugs for all my vehicles and change
>them out at each 30K. The truth to be known there is no proof that a more
>expensive plug provides better performance whether it be a platinum , or
>split fire, or any other type. See for yourself write each manufacturer and
>ask them to provide a guarantee and if you are lucky to get an answer you
>will find they will not provide one and they will provide many excuses.


Double platinums are genreally designed for lost spark ignitions,
because half the plugs fire positive, and the other half negative.
They are not a great improvement on conventional ignitions, and using
non platinum plugs on my old 3.0 Aeostar (ford) I got over 40,000KM on
a set. Never liked leaving them in much longer than that anyways, as
they tended to "burn" the case, and you'd twist them off trying to
remove them. Not nice on an engine where you have to do everything by
"braille".