Just to get a feel for what people are primarily using - copper, platinum, iridium, unobtainium - fill out this brief survey:

Ye Olde 2006 Spark Plug Survey

Brand:

Model:

My idle is: Smooth/Pretty smooth with an occasional stumble/Kinda rough/I'm lucky if I make 8-seconds

Other comments:


Thanks!
Zach Zaletel
Anchorage, Alaska
1990 245 w/238xxx mi and front hubs that don't wobble, but a water pump that wants to retire soon...

Bosch or NGK, you can't sort 'em unless one has a rebate. Check the box, they're all made in China anyhow.

NGK BP5ES. (Hotter plug to prevent carbon build-up)
Smooth idle.

Tried Bosch with four electrodes but they did not work so well in my B230K.

Erling.
--
My 240 Page

I use NGK BPR6ES. They are cheap and idle smoother than any bosch plugs. All you really have to do is put a new NGK next to a bosch or a champion. You can see the difference in workmanship. The threads are smoother and shiny all the way around with no metal shaving anywhere. Not saying looks determine how well a plug functions but quality shows in more ways than one.
Also use different NGK coppers on my 960. Much cheaper than 3 prong volvo plugs with better quality.

Plugs: Bosch WR7DC for all except the 245T we just sold, which took WR7DS

Idle is: occasional miss or roughness, but a strong idle on all the cars.

In my experience the NGK's seem to equal the Bosch for performance. Meanwhile, Champion makes a similar looking piece of total crap.

Volvo plugs are always a good sign: it means the last owner used to take it to the DEALER, of all things!
--
Rob Bareiss, New London CT ::: 87 244DL- 249K, B230F/M47, Turbo sways, Bilsteins, GT braces, Virgos, Turbo exhaust, Gislaveds for winter!

I have tried Volvo, Bosch Copper, Champion, Bosch Platinum, Bosch Platinum+4, and Denso Iridium.

I'm not sure I could claim that it makes a lick of a difference. But I felt warm all over after putting the Iridiums in.

Long life in the plugs doesn't really interest me - I get the urge to take things apart every so often.

NGK BP6ES in the older engines, BPR6ES in the newer ones. I have tried everything else, and nothing is as good. Multiple electrode plugs, and precious metal plugs, require a higher firing voltage than copper single electrode ones, and I won't use them. After Bosch's abortive attempts at the first type of platinum plugs in the 1980's I never used that brand again.

Ran Bosch Copper core for years until they got hard to find.
Switched to Bosch Platinum until the center electrode broke on two of them at once during a -30 Degree start attempt. Been running NGK V groove plugs ever since, awsome idle and easy startup and easily last 30K without cleaning. Also had great luck with them in Turbo applications.

I am considering the use of the unobtainium plugs dipped in Dihydrogen Monoxide, I hear they double the spark energy without even changing the coil or wires! I also heard that they improve gas mileage by UP TO 50MPG

jorrell

NGK... BP6ES (should be an 'R' in there somewhere). Idle is as smooth as a big 4 can be, even with a VX cam.

Standard Bosch plugs didn't seem to last as long; Bosch platinums resulted in harder starts and rougher idle.

Now on the 850 with the 4-valve head, it's a totally different story...

NGK based upon recommendations from the Board. Good idle, long life, and decent cost. The cars ddefinitely like 'em better better thab Bosch brands.
--
Six bricks, yep, six!

Brand: NGK

Model: BPR6ES

My idle is: Pretty smooth with an occasional stumble

Other comments: I have used Bosch exclusively in my VWs and BMWs for 20 plus years. When I first got the Volvo 5 years ago I put in NGKs. Ran good. Switched to Bosch and idle was not as good. Just pulled the Bosch. They were clean and still within gap spec. I replaced then anyway with a set of NGK and the idle is much smoother. If I cleaned the throttle body the idle would probably be completely smooth.

Have used bosh 3 prong design in my 960 since new-now have 235k miles on her and the last 10k have been with the E3 plug from auto zone, smoothest idel ever and even with 10k on the plugs there is no stumble-liked em enough that I traded the plugs in my 525i bmw also. They are pretty durn good
Poolman

Factory Volvo in everybody's car that I service and if I need a set of less expensive plugs I will run Bosch supers.

Mark