I changed the spark plugs for the first time. The van came from
Colorado, and Bosch W8CC's were installed. I installed the W7DTC's,
which are the tri-electrode type that are recommended by some.

I drove the van for the last 3 months with the W8CCs and my around-town
mileage hasn't been that great (about 200 miles to a tank). After
driving the van about 10 miles to fully warm it up, I turned it off and
waited a couple of hours. Then, when I pulled the W8CC's, they were
black with carbon except for the electrode, which was brown. I'm
thinking that the van was running a little richer than necessary, maybe
because it was used to the 5000 ft elevation of Colorado. I'm hoping
that the slightly hotter W7DTC's will improve my mileage. The van seems
to run really well with these plugs, though!

Dan