My oil filter drain bolt was feeling gritty,so I was going to fill it up with aluminum foil rolled up in a ball.I just couldn't do it. Seem cheezy it would work,but cheezy. I sprayed some pb blaster in the drain hole to clean the threads out, it wasn't filling up,the pb blaster was going somewhere. I ended up taking the inner clutch case off,I had pb blaster sittting at the bottom of the clutch cover and transmission linkage. Once the drain bolt is removed you have a clear hole leading to the clutch area,once that bolt is removed you have a open end leading to the cases,so I do not suggest spraying contact cleaner or drilling a hole for a bearing to fill it up. You can do this,but do it with the inner clutch case off,or all that crap is going to mix with your oil. I ended up cutting a small piece of 6 gauge copper wire trimmed a little so it will fit in the hole,I wedged it in nice and tight. I have to say,after I cleaned the threads out this is the smoothest the drain bolt went in.Before I had to use a socket AFTER ONLY 3 TURNS,now I can tighten it up all the way until it bottoms with my fingers. I definetly see these threads stripping in the future if you do not fill that hole. NICE CATCH grey.