Originally Posted by chad177
That's not at all what he needs.
If you go to any auto parts store, in the section with the replacement drain plugs, they have plugs for just this purpose. They are what's called OS (which stands for "Over Size") threads. You want to get one that is labeled "M14-1.50 OS" (again, the "OS" meaning oversize threads). It is fluted on the end so that it cuts the hole with new, slightly larger threads.
To helicoil as Hypnos suggests is a great idea too, but keep in mind that to do that you have to pull the pan. (BTW - to replace the pan, you don't need to pull the entire engine - the pan is removed without doing that.) If you're going to pull the pan, you might also consider just replacing the pan with a new one. The helicoil will be much cheaper, but the same or slightly more work.
The risk with helicoiling (and also with going to the M16-1.50 larger plug) is that you do have to drill and re-tap the new threads straight or the plug won't quite seal due to being slightly crooked relative to the gasket surface.
If you do go to M16-1.50 plug (which is a standard size replacement oil drain plug that you will find in the auto parts store), you will find the tap from Snap-On. That is a very hard-to-find size tap, but I did track it down at Snap-On when I was having to make the same decision that you are making now.
As far as a decision between going to M16 plug or helicoil, you might as well helicoil it - the helicoil will be infinitely stronger than anything else you could do, so it will *never* strip out. So between those two options, I would go with helicoiling.
To sum up, here are your options with the pluses and minuses of each:
(1) OS plug - very cheap, very quick. Will work fine - just be careful not to be too aggressive in tightening the new OS plug, because the OS threads won't be completely formed (i.e., won't be quite as strong as original threads).
(2) Helicoil - relatively inexpensive, but requires pan removal because you have to drill and re-tap the hole, and there's not room for that with the pan on the car. Super strong when it's done. Must be sure to put it in very straight in order not to leak (or pay a trustworthy shop to do it).
(3) Drill and tap for larger (M16-1.50) plug. Not a bad solution - also requires removal of pan. Though the M16 threads will be significantly stronger than the original M14 threads, for about the same amount of trouble, helicoiling would be a better choice because of the unbeatable strength of the helicoil.
(4) Replace pan. Additional cost, labor of replacing pan. Restores everything to original condition.
I'm not trying to sound like a know-it-all on this - I just studied and researched it a lot when I had the same decision to make. I initially went with the OS plug, which worked, but for some reason leaked a little (I think it was a teeny tiny bit tilted and so didn't seal against the hard washer - probably would have sealed fine against a slightly softer washer. Eventually replaced the pan after a disasterous attempt at helicoiling.
You do what makes sense to you. At least now, you have the info. to make an informed decision.