To not start a new topic, I broke mine off this past weekend and it was impossible to find a replacement (napa is closed on weekends around here, just O'Reily's) at a store. It seems to be a M16x1.5. A locally owned oil drain place had a Subaru engine oil drain plug that was a M16x1.5 but had a M14 Hex head on it with a M24 washer. They gave it to me for free, even though I offered money. It fits and doesn't leak, but lacks a magnet on the end like the stock one had. I guess I'll search the internet or Napa for an oem replacement.