Onan 4K spark arrestor plug won't loosen for removal

Over on the SmokStak forum they said they are hard to get out, and if you try you should use vice grips on the mounting boss, otherwise you can rip it right out of the muffler sheet metal.

But the guy said once he got it out, hardly anything came out of the muffler anyway so it probably wasn't worth the effort.

Kroil is another good penetrating oil. I tried it on mine and gave up trying to get it out.

Steve