The reason the oversize plugs often leak is that they have a tendency to tilt a little (not follow the original threads) - the tilt causes the plug head not to seat flush to the hole land. Dorman very stupidly puts a hard washer on the plug, so it can't squish and compensate for the tilt. The solution is *not* to tighten it harder (the threads are weak, and you could strip them again long before it seals) but to put a softer washer in place of the hard one, and replace it with every oil change or every other oil change if it takes a set.
I don't think the Fumotos and similar come with oversize thread (likely because they realize that they too would have the same problem of not necessarily forming new threads straight), so you'd have to tap to the next size up. You are asking about epoxying it in, so I guess that would work - a little risky. I'd use nothing but J-B Weld on it if that's the way you go.
My only complaint about the Fumotos (and pretty much all similar solutions) is that the pee hole is relatively small, so the flow is lower and so drawing of particulates off the bottom of the pan floor is not going to be as effective. That doesn't bother most people, and I realize it's not a huge problem - I just like the drain to have more of a flushing effect - otherwise I'd probably be using it or something like it. A lot of people use them, love them, and have no problems.
But yeah - once the threads are stripped, you have to improvise to put a Fumoto in - either tap it larger or helicoil it (making sure not to tilt it in both cases - can be a little tricky to guarantee that) or, like you said, epoxy it in.
'98 LXi - Later Concorde gages (black w/ chrome rings)/'99 LX - LHS gages (white) - HIR bulbs
Last edited by peva; 12-03-2012 at 08:44 AM.