Rusty, one can take a sparkplug that has a longer threaded section that matched the thread pitch and diameter and it will thread through the sparkplug hole and into the combustion chamber.
Sparkplugs do not have interference pipe threads.
Excess oil in the combustion chamber, pressurized by the piston compression process will have the oil pushed around the threads and up to the sparkplug body.
Remember there is compression in the combustion chamber before there is combustion.
