Stubborn Spark Plugs: how much force is too much?

I picked up a 2nd gen v6 tacoma about a year ago with ~90k miles and am doing all the maintenance myself...just getting around to the spark plugs. I have a sneeking suspicion that they've never been touched on this vehicle

I've never done spark plugs before, and am expecting a bit or resistance with them if they haven't been replaced since the factory - so i'm trying to get a feel for how much you can crank on them before they sheer out and create a huge headache

watching this guy on youtube slowly work out some stubborn plugs gives me a better idea (i'd probably soak them with kano kroil / wait for a few hours or overnight / heat cycle the engine and pull out cold /etc etc), but just wanted to post and see what people have to say...

how much force is too much while trying to work out stubborn/seized spark plugs?

 

Hard to say how much is too much. Everyone will have a different threshold feeling. I did deal with a stuck plug in my daughter’s 07 Corolla last year. It turned maybe an eight of a turn and no more. I soaked it overnight with penetrant. The next day I made some errands. Once home, and with the engine still hot, I slowly worked the plug out. I don't recall what penetrant I had at the time. It would have been Blaster or Liquid Wrench. Yes, I was sweating that I was going to damage the threads in the cylinder. I had seen mixed videos on whether to remove the plugs with the engine cold or hot. I reasoned that aluminum has a higher heat expansion rate. It worked out for me.

 

too much is when it breaks. too little is when it stays in the block. just right is if it comes out in one piece.

there's really no differentiation between them, just sort of a lottery.

 

Thanks to both of you for your wisdom I guess prayer is the only real prescription