Reman engine installed a couple months ago. I've done 2 so far. Both times the plug doesn't seem to want to get snug. I feel like it will strip if I try tightening any further.

It did not have a plastic washer on the plug when I changed it at 500 miles. It had a steel washer. No leaks.

I just changed the oil again at 3,000 miles and put a plastic washer on with the steel one. Still doesn't snug up nice. It may if I try more but I'm afraid to. Doesn't feel right. Reman company tells me it should be tq'd to 25 ft lbs but on a second call to them they said 20 ft lbs. What should it be and what kind of washer does it take? I believe it's still a 14mm.