I'm about to pull the trigger on:
BOSCH Part # 7900 {#7500, W7DC, WR7DTC} SUPER PLUS
From Rock Auto, like $1.29 each. From what I keep reading this is the way to go but it seems like there is a big difference of opinion on spark plugs here.

Its for my 1988 928 S4. I have no idea when the plugs were changed last (at least 2 PO's ago) so it is due.

 

Those are fine. Replace every two years.

 

They are both OEM on my 1990 S4 and 1987 924S. If you have a NAPA near you, they stock them and are the same price as Rock Auto.

 

Really?

Rock Auto is dirt cheap. I can't quite figure out their operation but they ship from a lot of warehouses. Maybe those are different distributors who list through their site. it would make no sense for one retailer to have so many variations on the same part available.

The trick I've found is to build a order from a small set of warehouses by adding a lot of parts to the cart and then removing the duplicate parts from "orphan" warehouses. They'll give a hint sometimes that a part is from a warehouse alreay in the cart but it's not always done.

Anyways...

If I need parts for a common type of car I'll always go there first. Worth checking for P=car parts, too, as they handle common maintenance items and some rebuilder items.

And oh yeah...

Get the basic copper plugs. Replace them occasionally. No need for tiny bits of fancy metal.

 

Great deal. I replace them every year. Easy to do and good for you also

 

My bad... NAPA is $.50 more expensive

http://www.napaonline.com/Catalog/Ca...900_0311872099

 

They come from the local Advance Auto store with a mail in rebate that brings the net down to that same price range. They also come from our 928 suppliers pretty cheap too, if you are already buying something else.

 

I went to my local O'Reilly and they say they can get them, but it calls for WR7DC which are the resistor version of the W7DC I am guessing. Is it the WR7DC that I want?

 

I bought the Bosch WR7DP Super Plus Platinums from Rock Auto. Got all 8 for under $20 with shipping.

I love Rock Auto. I get a lot of odds and ends from them. My last purchase was the small connecting pin for the rear wiper blade to the wiper arm. I found the same size was available for Acura/Honda's and got a set of 10+ for about $3.00 total.

 

WR7DC is what you want.

 

FYI from the NGK FAQ :;

Resistor Spark Plugs.


NGK strongly recommends using resistor spark plugs in any vehicle that uses on-board computer systems to monitor or control engine performance. This is because resistor spark plugs reduce electromagnetic interference with on-board electronics.

They are also recommended on any vehicle that has other on-board electronic systems such as engine-management computers, two-way radios, GPS systems, depth finders or whenever recommended by the manufacturer.

In fact, using a non-resistor plug in certain applications can actually cause the engine to suffer undesirable side effects such as an erratic idle, high-rpm misfire, engine run-on, power drop off at certain rpm levels and abnormal combustion.

 

There are resistors in the plug wire ends and the distributor rotor(s) which reduce EMI.


Running a non-resistor plug won't gain you anything, unless you widen the gap to take advantage of the extra voltage available.
In fact, just like a precious metal plug with a tiny tip, if you do not open the gap, it may run worse.

A larger gap improves part throttle performance, and may lower emissions.


I have dynoed as high as 325 rwhp on a cold day (IE UNC) with my S3 manual using NGK non-resistor with a 1.0mm gap.
Obviously, the plugs were not being 'blown out'.

 

Thanks all!