Date:         Fri, 23 May 1997 07:19:29 -0700
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         "Michael A. Radtke" <m.radtke@az05.bull.com>
Subject:      RE: re. Bosch Platinums

"The Platinum's corroded and wore so badly ... "

This list has had this thread before, and I am always curious as to what is 
meant when folks have a bad time with these plugs.  Testimony is often hard 
to interpret.  Above, I don't know what corrosion nor wear on a spark plug 
even means.

I just replaced my Bosch Platinum plugs after 50,000 miles on them.  This 
is what I found:

1) Even tan coating on all surfaces that were exposed to
   combustion.

2) The center (platinum) electrode appeared to still be flush with
   the ceramic surface.  However, this is hard to tell since it is
   so small.

3) The outer electrode badly worn.  All sharp corners gone, and the
   gap area eroded to almost twice the normal gap (.050 inches).

Now for my testimony.  I changed the plugs because I "perceived" a loss of 
performance.  However, I never saw a drop in gas mileage.  After the 
change, I "perceived" that the expected performance had returned.

Disregarding my perceptions, I conclude from the inspection of the plugs 
that 50,000 miles is perhaps a bit too long.  I think that I'll keep this 
set for about 40,000 miles.

Mike


Michael A. Radtke  -  Z74               Voice: 602-862-4897
Bull                                      FAX:         4853
13430 N. Black Canyon Hwy.
Phoenix, AZ  85029                      Email: m.radtke@bull.com