Here are the threads- Once it broke loose it came out easily so it was just stuck. I assume it’s normal to see the valve like this ? Finally should I be concerned about the penetrating oil that for sure got into the cylinder?

 

A small amount won't hurt anything and will quickly burn in combustion. If a lot got into the cylinder, you can leave the plug out, pull the fuel pump relay, lay a shop towel over the plug hole and weigh it down around the edges, and crank the engine a few times to eject as much of the penetrant as possible, then reassemble. If you don't lay the towel over the hole and weigh it down, penetrant will spray everywhere (don't ask how I know...).

 

Fantastic result! Well done, and well done to Don with the Mayhew extractor tip.
Which mix did you use for penetrant?

 

Doesn't success feel good! Defeated the problem, instead of the other way around! Glad those square easy-outs eventually did the job. ATF+ Acetone was a great recommend too.

BTW, the next thing I'd suggest is to buy a proper tap, and *chase* all the plug threads with some heavy cling grease on the tap flutes to catch any shavings. A spiral tap might let less fall in that regard but... any tap is better than no tap. And I'm with Greg. I'd rather use A -Seize even if it means I have to mark the plug so that it's electrode indexes properly - and stop at the right spot even if it's under-torque.

~PK

 

I have used left handed bits a number of times. Seems the heat and vibrations loosen the broken bolt,.