I only replace spark plugs when there the electrodes are getting warn, like
rounded or thin,  the gap is getting too big........or if a plug isn't
firing right, of course.
That's for conventional plugs. For platinum plugs .........I run those as
long as they are working properly.
I normally get the very best spark plug I can , which usually means
platinum, though I also have not found platinum plugs to be 'the ultimate
final solution' ........but when they're workin' like they should - it's
what I prefer.
I always put an anti-seize compound on the threads of all spark plugs.
It's also good to not just leave them in any engine for years and years -
the can get stuck badly.
Non-professionals often don't tighten spark plugs tightly enough, in my
expereince - seen lots of loose ones.

Scott
www.turbovans.com
----- Original Message -----
From: "Don Hanson" <dhanson928@GMAIL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Tuesday, May 12, 2009 5:20 PM
Subject: How often should one replace sparking plugs?

>  On these small injected motors, how long is the average plug life?  Mine
> is not a WBX but it had Digifant and it's pushing a van and it's
> a teenie-weenie 1.8 liters of VW power.
>
> Every year?  Every 20k miles?  Anybody want to recommend an interval?
> When
> I got the van about 30k miles ago, the plugs were  quite 'eroded'...the
> gap
> was up at about .040 or .050 but it was still running and starting
> 'normally' and I didn't really notice any gross improvement when I stuck
> in
> some new plugs..  Just doing my spring maintenance, Oil, all filters,
> change
> tranny oil, spray lube all the suspension, alignment check, wipers, etc
> etc.  Plugs and cap, too?
>
>  Don Hanson