So when I got the cheap sears oil change that I'm using now as a bit of a engine flush they informed me that it looks like It already has been a bit beat up and an oversized plug as been put in place of the original. It wasn't leaking before, or if it was it wasn't enough to notice. Dart has been sitting in the garage for like a week as I haven't had time to do much to her. Today I glanced under the car and the drop cloth is wet. Oil level is still okay so Its not loosing quart or anything.. but I want to get it fixed.

My idea for a nice cheap and reliable fix is to get a Fumoto Valve in the correct size and put some JB weld or something on the threads, put it in there and forget about it. I've used the Fumoto valves on other things and never had an issue, so I'm not worried about its integrity. Get one without the nipple and it doesn't stuck out that much further than a standard plug. also really does make oil changes a breeze.

My issue is what size to get? I know the stock plug is 1/2" - 20. If I have a single oversize, or possibly a double oversize what size would those be? How much is the over size plug over sized? I want to make sure I get something close enough to fit tight so that the JB Weld or whatever I use is mostly just to insure integrity and prevent seepage.

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1968 Plymouth Barracuda [Daily Driver]
1972 Dodge Dart Swinger [Lent out as Daily Driver to a friend]
2010 Challenger R/T 6 Speed

I don't think the Fumoto valves come oversize. Oversize drain plugs are just that - they are designed with a larger than normal diameter and the same thread pitch as original. They are a 'special' thread.

Usually the oversize is marked on the head.

Right, I know that part. Fumoto do come in pretty much every mm between 10 and 20 though... So the question is how much bigger is an oversize? All the Oversize I find just say is either 1 OS or 2 OS over stock. But not a mm difference between stock and the Oversize. If I know that I can pick the appropriate Fumoto offering.

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1968 Plymouth Barracuda [Daily Driver]
1972 Dodge Dart Swinger [Lent out as Daily Driver to a friend]
2010 Challenger R/T 6 Speed

I pulled a couple of drain plugs off the shelf & checked. A 14mm x 1.5 drain plug had thread diameter of 13.85mm, while Single Oversize was 14.25mm (.4mm or about 0.016"). I'll assume 1/2" OS has a similar increase in thread diameter over std 1/2" while keeping the 20 pitch. If Fumoto's come in "normal" sizes & you have OS, then I wouldn't try it- I love JB Weld but I wouldn't trust it to hold that much of a size mismatch.

However, 20 pitch is very close to metric 1.25mm pitch, so you could tap the drain plug hole to 14mm x 1.25 & use a plug/ valve for that size.

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63 Valiant Wagon
225 - 4 bbl

WagonsRcool,

Thanks for the info and suggestions. I was looking at a Futomo that is indeed in 14mm x 1.25(F-111) as a possibility, which sounds like it would work as you're suggesting.

Can't hurt to try. I'll know pretty quickly if it seems like it will hold, the JBweld would then insure a seal. I'll think I'll give it a shot and let you all know how it goes.

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1968 Plymouth Barracuda [Daily Driver]
1972 Dodge Dart Swinger [Lent out as Daily Driver to a friend]
2010 Challenger R/T 6 Speed