Plumbers pipe dope paste on the threads works fine.

 

My $0.02: This plug is an example of the occasional design decision coming from the MoCo that is driven by cosmetics over function.

Putting a tiny, steel plug into an alloy case with tapered threads makes no sense unless you're trying to make the plug look like just another mounting bolt. This is form over function, probably driven by concerns over customer acceptance of the switch to a wet primary.

The right way to design this is like any other plug: Standard threads with a flanged bolt/plug and a gasket or crush washer. But that would look more clunky.

I concur with the Teflon tape. Couple of quick wraps (no need to bother with trimming it) and go easy on the torque.

 

Mine is a standard plug with gasket/washer.

 

What year/model?

 

1985 fxwg

 

That has the old style where the drain plug is on the inner primary, right?

 

Yes.
original poster didn't give a clue what he has.

 

I chased a that same plug drip, trying everything mentioned except retapping...turned out it was the starter jackshaft seal that ran down the back side of the inner primary but left no visible trail because the black texture on it. Removed the inner primary and replaced all seals and it was gone, hasn't leaked a drop for years

 

Sorry, 1994. I had the impression it was the same across Evo land but perhaps not.

 

FWIW … on both of my 1996 models I removed the tapered plug … drilled and tapped to 7/16 fine thread … used a stainless socket head cap screw … under cut the bottom of the head to accept an o-ring … same o-ring that is on the tappet screen …

when I change primary fluid I put on a new o-ring and use a small amount of Teflon tape … no leaks or drips