[F10Dan]

The newtis instructions clearly state not to grease spark plug threads. What is the general wisdom here?

For the past 30 years, I have put the slightest touch of aluminum anti-seize on all my plugs. The fear is frozen plugs in the cylinder head. Seems like common sense to me...

Why is BMW so explicit about not doing this?

Is the concern over-application and the plugs backing out?

Is this a non-issue and I should quit second guessing the engineers and just do what they say?

[Surly73]

Originally Posted by F10Dan

Why is BMW so explicit about not doing this?

When threads are lubricated it reduces the torque reading on a wrench for a given amount of bolt stretch. This means you effectively overtighten anything that has had anti-seize applied (unless that was taken into account by TIS).

I believe this is the origin of the explicit instructions. On anything newer than an M52 I've been following BMW's instructions.

[agentorange]

Originally Posted by Surly73

When threads are lubricated it reduces the torque reading on a wrench for a given amount of bolt stretch. This means you effectively overtighten anything that has had anti-seize applied (unless that was taken into account by TIS).

I believe this is the origin of the explicit instructions. On anything newer than an M52 I've been following BMW's instructions.

We tighten spark plugs to yield these days?!?!

[Cvx5832]

Originally Posted by agentorange

We tighten spark plugs to yield these days?!?!

Proof load vs yield strength.

[F10Dan]

Sorry guys, I’m not a tech. What does yield vs load mean?
Also, what should the plugs be gapped to? I would like to confirm proper gap on the units shipped.

[TEF]

Porsche has a similar view about plugs and anti seize, but with a slightly different take. Their rationale, I am told, is that the aluminum-based grease could short out a plug if its put too close to the tip. Frankly, both reasons seem a little odd particularly if one does not routinely over tighten plugs or slather on too much anti seize. All things considered, it seems preferable to removing a seized plug from an expensive aluminum head.

[F10Dan]

Originally Posted by TEF

Porsche has a similar view about plugs and anti seize, but with a slightly different take. Their rationale, I am told, is that the aluminum-based grease could short out a plug if its put too close to the tip. Frankly, both reasons seem a little odd particularly if one does not routinely over tighten plugs or slather on too much anti seize. All things considered, it seems preferable to removing a seized plug from an expensive aluminum head.

I agree. I’m going with my gut on this one and will put the slightest amount on the upper half threads.

[BTTW]

Stick with what works for ya. 15 years working at Acura, using NGK or Denso, we’ve never once had to deal with a plug that didn’t come out easily unless it was butchered my someone. I’ve personally never applied anything to the plugs, but if it works for ya...