engine oil drain plug fitment

What is your question?

My 2013 Mazda has a fairly new (two years ago) engine oil drain pan. I change my own oil. I have a hard time tightening the drain plug so it doesn't leak. I am using the metal washer as required as far as I know. I cringe when tightening the plug, thinking I am on the verge of stripping the threads, and it still leaks. Is there a proper spec for ft/lb to tighten it? I have a torque wrench. Is it possible the oil pan fitting area isn't flat? Is there a different washer type (collapsible?) I might use instead of the standard flat metal?

How long has your 2013 Mazda 3 had this problem?

More than a year