This is question came up while trying to diagnose ignition coils unseating. I used anti-seize lubricant on the currently-installed spark plugs.
I'm planning to install a new set of three NGK DCPR8E spark plugs in a Rotax 1503 HO in a BRP RXT-X aS 260. There is disagreement between the official advice from BRP and NGK on the matter of lubrication. (I haven't found any advice direct from Rotax but BRP owns Rotax and the BRP manual seems pretty complete for engine maintenance.)
As you can see from the exerpts below, BRP recommend using anti-seize lubricant while NGK recommend against any lubricant.
On the one hand, I'm inclined to omit the anti-seize lubricant to see if the ignition coils stay seated. On the other hand, this is in a salt-water marine environment so I'm concerned that the spark plugs might seize to the head without the anti-seize lubricant. I'm hoping someone has some other reason or strategy to do one thing or the other.
Also, suppose I opt to follow the NGK recommendation an use no lubricant. How do I clear the remaining lubricant from the threads in the head?
The BRP manual includes the following text in the spark plug installation procedure:
Installing the Spark Plug
- Apply LOCTITE 767 (ANTISEIZE LUBRICANT) (P/N 293 800 070) over the spark plug threads to prevent possible seizure.
Page 8 of the NGK catalog includes, among other things, this text:
SPARK PLUG INSTALLATION TIPS
• NGK does not recommend the application of lubricant to spark plug threads as the resultant reduction of frictional forces at the thread faces will render the torque charts inaccurate and over tightening could occur
For what it's worth, the back of the spark plug box itself has this advice:
I can guess at what those symbols mean, but it would just be a guess.