aTOMic

I think most modern plugs have an anti-seize type coating or plating on the threads (Bosch uses nickel plating). Check the manufacturer's site for the brand /type you used.
As for lubing/ oiling the threads, unless the service manual states to do so, you are treading on dangerous ground, as a "wet" torque is much closer to the failure point of the threads. Torque specs are for dry assemblies unless otherwise noted. Ask any tribologist.

Edit: EZVDub posted an excellent pdf link while I was off looking for info on Bosch's site.

Just Me

same here. I understand the arguments against, but a little care and prudence seems to eliminate the ill effects.

g

SloopJohnB@mac.com

Second. Also for 30+ years. Never broke a plug with antiseize but did have a problem ONCE with a non-antiseize plug on a 1973 Kawasaki Z-1 900 cc DOHC L4 motorcycle engine with an aluminum head I bought new in 1973. First Z-1 in Texas. Plug seized and damaged the head upon extraction. Had to install an insert but didn't have to pull the head. Engine went on to live a full life, sold the bike in 79.

Damndest bike I ever owned...3000 miles on plug changes and the bike wouldn't start if you didn't. Point ignition and the plugs looked like new, milk chocolate brown when they came out. But. It. Wouldn't. Start without new plugs every 3000 miles.

SloopJohnB@mac.com

I agree...I'd rather eliminate plug seizing and attendant thread stripping and head damage and take my chances with other problems. A little antiseize goes a long way.

ezveedub

Most plugs now a days have anti-corrosive coatings, but when the spark plugs are exposed, is when you run into issues. NGK states not anti-seize on new spark plugs. If you remove them frequently and reuse them, you may want to apply anti-sieze at that point. You torquing of the spark plugs will be more critical though when re-using them. As for a C5 A6, when using platinum plugs, your not replacing them for another 40K miles.

Huskerbob

I have never NOT used anti-seize on plugs in aluminum heads. Starting back in the 80s at my motorcycle shop we always used the stuff. Just be careful to roll the threads on your finger to get the excess off before you drop them in the holes. Nothing more fun the trying to helicoil a sparkplug hole in a thin alumininum head.

A6Gary

If spark plug threads are not coated, they would show evidence of corrosion just by being exposed to moisture in the atmosphere. I also have not used anitseize on spark plug for any engine with an aluminum head.

ivonius4.2

Actually it's GALVANIC corrosion in the absence of water, but you still get corrosion! Galvanic corrosion will occur when two different metals, each with their own electrical potential (ability to hold their electrons), are placed together - the flow of electrons from one metal to the other results in corrosion to the metal. The further apart two metals are on the galvanic scale the more vigorously they will react. Although Galvanic corrosion is most active when an electrolytic solution such as water is present between the metals, it can occur when it is dry if the metals are touching. I'm just sayin'..... you all decide for yourselves.

SloopJohnB@mac.com

I just looked carefully at the box the NGK individual plugs come in. There is no torque specification per se....for cone seat plugs NGK says 1/16 turn past finger tight. For standard metal gasket washer plugs NGK says 1/2 turn past finger tight.

I see no problem with antiseize with this specification other than the plugs might not be tight enough to avoid backing out. However, I've never had a plug back out either.

jseklund

I have always used anti-seize on my spark plug threads. I'm actually quite liberal with it - not enough to have goop on it, but I make sure there's a nice coating on all the threads and that it doesn't get to the electrode. It was just the way I was taught to do it, so I never thought much about it.

As Ivonius points out - galvonic corrosion can occur between two metals any time they are touching. This can be a disadvantage, but can also be used as an advantage - helicoils are often stronger than the original threads because of this principle I believe. Still, I would prefer not having to tap and thread helicoils into the head of any engine...

Because of this thread, I may be a little more conservative with the amount of anti-seize I use....but I'm not sure I'll stop using it. On the 5 cars I do tune ups on, I've never had a problem with any from the antiseize...at least not that I'm aware of.