SUMP PLUG REPLACEMENT!

[t0rxe]

The sump plug in your photos 'fearfulmaster1' looks the same as mine, and when I replaced it, I replaced the aluminum crush-washer with a new genuine one from Mitsubishi (it's only about $3.00 or so). They don't fuse, but the old oil becomes somewhat 'sticky', so it has a tension bond to the plug itself. Just get a Stanley knife and work it off from each end.

If you're really pedantic, before installing it back into the sump, clean the old bolt in petrol, and put new oil around its threads and under as well as around the new aluminum crush-washer when installing it to help make a good seal with the sump (exactly the same principle like when an oil filter is installed, minus the petrol cleaning part obviously).

As for replacing the bolt, it should only be replaced if the threads are damaged or the socket (tool) used to remove it has started to strip or make the sides of the bolt malleable which would cause removal of the bolt to be substantially difficult due to the torque-wrench or ratchet slipping. I really couldn't imagine this next scenario happening, but yes, the sump is indeed a harder metal over the bolt itself to avoid thread-stripping of the sump. So another reason to replace it might be if you have oil leaks (since the threads might be off-par with the sump threads, thus the threads themselves have wider gapping allowing oil to pass through).