Need help finding OEM spark plugs

[Big L]

2001 Cadillac Deville DHS

Which plug should I use? 41987, 41929 or even 41-937? Does anyone have my car, and if so which did/do you have?

All Listed plugs have a gap of 0.050
Autozone – AC Delco 41-987
Kragen – AC Delco 41987
Alldata.com - AC Type 41-929 (Cannot find plug)
GM Service Information - Document ID# 507608 lists Nipendenso Type 12561466 Gap: 1.27 mm (0.050 inch) When I cross reference 12561466 Rock Auto lists them as 41-987
Local Dealer – 12571535. When this is cross referenced this Rock Auto lists them as 41-987
Haynes Manual – AC 41-937 – I know someone said not to use the Haynes
but this was actually my last check as I was curious.


Can I not buy OE plugs or is this it? If these fit, why would so many different part numbers (and different plug specifications?) come back to 41-987? I am still concerned about the 41929 from alldata.com. Granted it is only one issue, but it’s one of 6 things I’ve researched on the site. And, the only part I’ve looked up so far. The information is still valuable, but should I trust their listed part #’s? Has anyone else had this problem? Not trying to be anal, it’s just a little odd to me.

[00 Deville]

The only plugs you should use in your N* are the AC Delco 41-987 they come pre-gapped to .050. Any other plug will cause mis-fires.

[Ranger]

Yup. 2000+ Northstar uses A/C Delco 41-987.

[submariner409]

AC Delco #41-987. RockAuto generally has a decent price. Torque each to 13 ft/lb. Here's what you'll be looking at...............

[Big L]

Good Deal. Has anybody had issues with wrong part numbers from alldata? I'd like to order a replacement radiator, and have it when I take the existing one out. Downside, cannot measure it and I am not 100% positive mine has an oil cooler line.

Is the model number accessible without taking radiator out? If so, any ideas on it's location?

[DevilleDeeman]

Originally Posted by 00 Deville

The only plugs you should use in your N* are the AC Delco 41-987 they come pre-gapped to .050. Any other plug will cause mis-fires.

Not true, I use NGK and never had any misfires or rough idling. NGK supplies alot of plugs to car manufacturer's including GM. My mechanic swears by them and has never had any problems. Just make sure you use the platinum for your Northstar engine.

[00 Deville]

Originally Posted by DevilleDeeman

Not true, I use NGK and never had any misfires or rough idling. NGK supplies alot of plugs to car manufacturer's including GM. My mechanic swears by them and has never had any problems. Just make sure you use the platinum for your Northstar engine.

You need to keep your fingers crossed...

There have been a lot of people on this forum that have had misfire issues with the NGK's. They are a lot cheaper than the OEM plugs. A lot of shops will use the cheaper plugs so they can mark them up more without the customer raising hell.

You really ought to learn how to change your own plugs... it's not that hard.

[submariner409]

Oil cooler lines (2) run from the oil filter adapter top case to the front of the radiator passenger side tank.

Look at the list of RPO (Regular Production Option) codes under the spare tire cover and enter all the 3-letter codes into www.cadillacfaq.com/rpo/index.php. You're looking for an RPO that specifies heavy duty cooling or a towing package. Chances are, if you don't have that, you don't have an oil cooler.

The cooler lines attach, with spring locked quick-connects, to the fittings shown.

In response to a question, this post refers to Post #5.