Why Change Your Spark Plugs?
Sparks plugs normally deteriorate slowly and constantly from new, and replacement at 30,000-mile intervals represents a reasonable cost/performance compromise. I had been advised by the local BMW dealer to use the same brand and type spark plug installed from new in the M60 engine. In my case they are NGK Copper Core BKR6EK.
However, I have recently installed the Bosch +4 platinum plugs (p/n 4417) and have been very impressed with the improvement in idle stability, smoothness, and off-idle driveability. There is no question they are a better choice than the NGK's. When I renewed the NGK's last year I was surprised that I didn't notice any difference on my first drive. The +4's are a different story - the most difference I have ever noticed from spark plugs.
How To Do The Job
This is one of the easiest and most fun jobs to do, and you can do one bank at a time to spread the job over two days. Allow 2� hours to do the entire job.
Remove the top engine cover via four 10mm screws under the round plastic caps. Remove the plastic covers over each head via four 10mm screws under rectangular plastic caps.
Each spark plug is driven by its own ignition coil. Remove the screws and slide each coil out, disconnecting the cable connector at the same time. Place the coils on top of the engine in sequence. They are all the same but there is no reason not to put them back in the same location.
Caution: Be sure there is no possibility that the ignition could be switched on inadvertently while the coils are removed.
Remove all the plugs and compare them. They should all be a light gray to a light brown in color. If you see anything odd, keep the set for future reference and mark them so you know which cylinder each one came from.
Clean the rubber insulator on each of the HT coils with a very clean cotton rag lightly wetted with isopropyl alcohol. Clean inside the tips by placing the rag over a small screw driver.
Clean the plug gasket contact surface in each plug hole. Use a �" drive extension or similar with a cotton rag wrapped and taped around the end. Wet the end with a solvent such as paint thinner and insert and rotate in each plug hole. Be careful not to drop anything down the plug holes.
A rag wrapped around a drive extension (top of photo) to clean the plug
mating surface.
Take note of any oil leakage you see in the head chamber area and clean it up. Check all the 10mm screws for looseness but do not overtighten. There is a service bulletin regarding oil leaks in this area and any serious leak should be deferred to your BMW dealer for advise.
Unpack the new spark plugs and take care not to touch the insulators. Apply a small amount of anti-seize compound (Prestone/Loctite make this) to the threads of all the plugs. Clean the rubber inside of your plug socket and install each plug using great care to avoid cross-threading.
Work the anti-seize into the plug
threads.