[Buddur]

Weird for sure. What is the timeline again? You pulled the plugs...then a mechanic came to your place and did a compression test...then you tried putting the plugs back in and found this?

I think the compression tester end that screws in came off the hose and is still in there...regardless what the mechanic said.

 

[Buddur]

Get a bolt extractor set, one for small diameter bolts/ends, as they have teeth that will grab and remove stubborn bolts etc. Use downward force and slowly back out whatever it is from the threads. Once fully removed from threads you may need a magnet to pull it from the plug slot.

or

 

[Buddur]

At this point it doesn't really matter what it is...what's important is to give good ideas how to get it out. Once it's out....then we'll know what it is.

 

[Buddur]

Not sure if someone who works around hydrocarbon odors all day is the best to determine where a similar odor is coming from....like asking someone from a wastewater treatment plant if he smells that stinky fart. You need to get on your hands and knees and sniff yourself, or have your kids do it, someone who has a more sensitive nose. Get your nose right on the seats, carpet, wherever, and try to assess the location or area yourself. It may have been the mechanic who sat in your car and unbeknownst to him had oil or gas or something on his clothes and accidentally got some on your seat or floor mat or wherever. Your nose knows, or can find out.