Here's some advice from someone who has knowledge about the triple electrode
W7DTC spark plug and others

"Malibu Tony" wrote:

> Since you guys with the 2.1L motor have the luxury of being able to use
the
> 4-electrode platinum plugs (jealous?).  I wanted to let the 1.9L people
know
> that they can upgrade to a 3 electrode Bosch Super plug .....part number
is
> W7DTC......I've had this setup in my 85' for years with no problems.
>
>Jon responds:

I've used that plug for years in both my 1.9L Vanagons and All my 5 cylinder
Audi engines...

You can also use the WR8DTC in high mileage engines that use a little oil.
It
is the next hotter plug in that range and it burns a bit cleaner, great for
stop
and go traffic too...

Just picked an '89 Jetta with the PF motor.  OE plug for it is a WR7DS
(Bosche
Silver).  A later motor in the A2 series also uses the WR7DS, but it states
that
the DTC is optional (it is a Motronic F/I system where mine is a Digifant
II,
that might be the difference).

I've always found it gives a hell of an improvement in performance over the
OE
copper plug, and it also does not foul as easily as the Platinum plugs.

            JonR

    NH area LiMBO rep

    Founding member of the NorthEast chapter of the Full Moon Bus Club
(wanna
join)