Plug finder
 

Recommendation: When looking for plugs on these vehicles, I would recommend looking at plug manufacture's website for what is the latest information: Example: NGK Spark Plugs USA. Technology has moved on since our vehicles were designed, engineered and screwed/bolted/welded together.

Without knowing your year, engine, etc I would recommend NGK Iridium IX® Spark Plugs as others have. Most of the V8 models have NGK OE, others have a mix.

Like others I tried the two and four prong Bosch plugs and replaced them with the fine wire Iridium NGK plugs, due to poor idle, Tip-in acceleration response, etc. My 2005 4.8is had NGK OE fine wire but not the better Iridium ones. Having worked for one of the plug manufactures earlier in my career, I would say finding the right plug characteristics for your vehicle is more important than "what came in OE". Most of that is due to changes in fuels being pumped today.

Note: Check the plug manufacturer's website for all applications not the distributors (resellers) as there are MANY errors on their sites.

TORQUE SPECS:
As mentioned, 23 nm /18ft-lb . note torque can be + or - 3nm. Multiple people have had the plugs back out if not torque to the higher number (20ftlbs for us US based owners) (Note: head should be cool enough to hold your hand on it)
Lightly lube plug threads with copper- based anti-sieze compound (IF not on plug already)

Replace your Coil on Plug Boots (if equipped) see the two types of coils images below. Part #2 on the right image. They just twist and pull off.

I recently replaced the plugs in my 2001 3.0i. They were original at 170k, but working just fine.

I replaced with the OES NGK as specified. Not looking to make a research project out of trying something different. Others may be better, but the OE ones were working fine at 170k, so ...

The main difficulty/risk/problem was removing the old ones. At 170k they were in there pretty tight. Some more than others. My main concern was not stripping out the threads when removing them. Patience, air blasts, WD40, more patience, and going slow and careful I was able to get them all out with no problems.

I _did_ use antiseize. I try to understand the reasons behind the things I do. If you read the official reports on this, their main concern is that antiseize will result in over-torquing due to reduced thread friction.

So what I did, and now will do all the time, is to follow the _angular_ torque specification, which you will probably find on the NGK box. For these, which have a gasket, the first time they are installed (i.e., before the gasket crushes) the spec (from memory) is finger tight and then 1/2 - 2/3 of a turn. To do that carefully I used a breaker bar, moving it 1/6 of a turn at a time - no ratchet makes it easier to measure the angle carefully since you can't get the full angle in one turn on these cars. BTW, I have 4 torque wrenches, so that's not the reason I think this is best.

Regarding comments on 100k changes vs. earlier. The manufacturers all want to sell their new cars advertising minimal maintenance requirements, so they say 100k. The fact that my original ones lasted 170k (no problems at all with the old or new ones - no change, not even placebo effect) shows that good plugs can last that long. In my opinion, the only reason to remove earlier than 100k would be to reduce the chance of ripping out threads upon removal.

Other more obvious tips:
- clean out the spark plug well as well as you can before removing the plug so nothing falls in to muck up the threads.
- I use masking tape (thin) to hold the spark plug socket to the socket extension, so they don't separate, leaving the spark plug socket stuck on the spark plug.
- I put dielectric grease on the rubber parts that need to slip off again one day

I replaced the plugs [almost certainly the originals] at 109k miles. Replaced with the NGK BKR6EQUP; I don't recall the torque, but I'm sure I followed the posts here [what StephenVa sez?]. No antiseize. I did them at the same time I needed to replace an O2 sensor, so I did the plugs and all sensors. I've since seen an improvement of maybe 1 mpg. Other than one brief period of hesitation/rough acceleration [cured by a couple tanks of Techron in the fuel], all good. I've heard criticism of the bosch platinums, but used them in an earlier bimmer [m52 six?] with no ill effects.

I'm gonna go with NGK platinum iridium 4 electrode... NGK hasn't failed me n my other cars, so I figure why not. Bosch for the new coils tho.

I have used NGK BKR6EIX ($7/each) on my:
- 1998 528i (E39) for 30K miles
- 2006 X5 3.0i (E53) for 10K miles

I will never go back to Bosch.

The NGK Iridium is simply superior. Not a single hiccup.
Smooth engine/rpm etc.

I use a small drop of antiseize and no matter what plug I use, I usually remove them at 45K or so for inspection: if still good, re-install them.

For Iridium, I replace them every 80K-90K or so.

^^^I used the NGK plugs that Riggo used, replaced at 65k miles just because they were original.

I am a bigger fan of NGK than Bosch plugs, I'm sure the Iridiums are fantastic.

NGK.
NGK are pre-lubed.
Torque according to TIS instruction.

Plug Update and comment on use of anti-seize by plug manufacturer
 

Update:
Anti Seize on plugs applied at the factory.
the IX Iridium have it installed, the OE Iridium ones do not. See the NGK, Bosch websites for details on your plug number and application info.

You need to confirm that the plugs you buy have anti seize on the plugs shell (The metal part with the threads vs the white porcelain part :D) As not everyone of the NGK, Bosch, etc etc plugs has it applied. See the part in the box to confirm.
Why use anti-seize? It is not a big issue on those who replace their plugs every 30K or so. It is a REAL big issue on those who run them for 170K (life time plugs?) Heat cycles, moisture, difference in metal to metal reaction builds a bond that may cause an issue where the next time the plug is removed all the threads come with it.

Bottom Line: Better to be safe than sorry. Oh and use a torque wrench set at 20 FtLbs will help too!