'07 Cobalt LS, vanilla 2.2
I may have to remove the (probably 10-year-old) spark plugs, which I suspect may be stuck. If so, I'm wondering if it would be prudent to hit them with an impact wrench to break them free.
In a word:
Please do not use an impact wrench on these. You run the distinct chance of stripping out all of the threads in the head, which will cause a huge nightmare for you having to have threads replaced (Heli-coil or the like). Just use a socket/ratchet and you'll be fine.
Use PB Blaster(the BEST),NOT WD-40(Water Displacement Formulation 40) or any brand of penetrating solvent,Liquid Wrench,etc. An impact wrench is a formula for disaster. Use a breaker bar to get the plug to move just a bit is good,apply more penetrant and,hard as it may to do so,WAIT. Days,even.If you can get the plug to move, even a bit counter-clockwise,re tighten it clockwise,then back the other way. Do this many times to slowly work the plug out. Be aware,muscling it out counterclockwise without going back and forth.counterclockwise,then clockwise, MAY damage the head beyond use. This is especially true of aluminum heads. Due to the plug threads reaching INTO the combustion chamber,Triton engines are very prone to damage when removing plugs. No matter what method is used on these engines,the head may be scrap when removing the plugs are attempted. By ANYONE,period.