Hey guys just wanting know what size o Ring the engine oil sump is mines old and starting to leak.

Should have an aluminium or copper washer on them not an "o" ring. Autobarn or supercheap would have a listing for a new sump plug and you may get the size from that if nobody can help you out. Sometimes just as easy to buy the new one as not that expensive especially if you cannot get to town with the old one off.
Most people put a new one on when they take the old one off so they have it to compare size with.
I Usually keep a selection in my gasket box for future use. Vee

Same size as a sparkplug (14mm). I use a sparkplug washer and it works well.

I bought a couple of aluminium ones from SuperCheap. They were . . . . err . . . .super cheap. lol Asked for 380 sump plugs to go on next oil change as well. Not quite so cheap. New sump plugs came with plastic washers, but I'm not game to use those.
You don't need to know the size, they look it up in a book.

Yup used the plasticcy ones in the past and also donot like them. They tend to give a bit on first use and have had them weep and also found the sump plug loose after a couple of weeks even though it was tightened to spec and on occasion torqued tighter on first use!! Back to aluminium and copper for me!! The red hardish felt type ones are ok as well. Vee

Yup used the plasticcy ones in the past and also donot like them. They tend to give a bit on first use and have had them weep and also found the sump plug loose after a couple of weeks even though it was tightened to spec and on occasion torqued tighter on first use!! Back to aluminium and copper for me!! The red hardish felt type ones are ok as well. Vee

I had a suspicion the might squash down and loosen the plug. Thanks for that, saves me experimenting. In the bin they go! lol

Thanks guys I was asking becausw I went past a mechanic and I brought some coil overs and my oils hitting 8ks I normally change every 5k... The guy said they all have different size I told him the nut is a 24.. He was gunna give me like 10 for free if I knew the size lol..

I bought half a dozen from Mitsu years ago, they are the same size as an ordinary tap washer or garden snap on connection but a bit thinner, should still be okay as long as you don't over tighten.
The original has an O ring not washer