The one that's under the oil pan.

 

why do you ask such a question?

It should be either 17 mm or 19 mm, fine pitch threads.

I think, I may be wrong.. anyone else?

 

just wondering. so is it 17mm or 19mm?

 

lol. mines a 22mm. wierd huh? i guess it got replaced before. I would tell you but im not at work and I cant pull my plug to measure the threads. probably a 17mm. I dont work on many rx7's at work so I'm not sure. Ask me a Honda, Toyota, Ford, etc.. I would probably know

 

My Turbo II is 19mm

 

slap a wrench on it and find out what size you got.

 

hmmm... this is confusing me. maybe I should have asked for the thread size where the drain plug goes to.

 

Guys, he's looking for the thread size/pitch. Not the size of the bolt head.

 

exactly thanks for pointing that out turbonut

 

bump ^ anyone please?

 

Just pull the bolt and have it matched.


PS: do this when you are changing your oil and have a bud drive you to the hardware shop. Find out what pitch you got.