DIY spark plugs

I recommend using a torque wrench to tighten the new plugs. Check your owner’s manual for proper torque. I’ve been changing spark plugs for 50 years, but only the past 20 in cars with aluminum heads. I’m afraid of stripping the threads in the head and the torque wrench eases this concern.

I agree with other posters about cold engine, hand tighten with extension, and use of never seize lubricant.

Personally, I don’t even know any mechanics who use a torque wrench on spark plugs. They prefer to do it by feel and this prevents overtightening the plugs. This is pretty critical on aluminum head engines.

Many torque specs are too high in my opinion and sometimes they’re just downright goofy.
Example. The manual for my Lincoln Mark (aluminum engine) gives the spark plug torque spec as “7-15 Ft. Lbs”. Which one do you use? The 7 is acceptable amd the 15 is not but many will assume the tighter the better so they will winch them on down.
With tapered seat plugs just nudge them tight. With gasket seat plugs run them in till they hit and then add a 1/4 turn.

Also check the plug gaps before installation. It’s commonly assumed that the plug gap is pre-set and cannot be adjusted. This is not true.