5/8 UNC refers to a thread that's 0.625" dia (just under 16mm) with a thread pitch of 11 threads per inch. (United National Coarse)

A standard metric 16mm bolt would have a thead pitch of 2mm or about 0.079" or about 12.5 threads per inch. So, they're not interchangeable.

Who are you ordering these plugs from? Any Mini supply house in the world should be able to get you a proper drain plug.

If this is a 1998, is it an MPi block?

Does the car have a carburetor or fuel injection?

The MPi blocks have a port for an oil temp guage. This does not change the oil drain location. if a mechanical cap tube gauge has been added, it will most likely have an adapter for the cap bulb in the transmission case. this would need to be removed to use the standard drain plug.

Pictures might help.

Terry

I measured the bolt and its thread size is 1.5mm. I order twice and got the wrong plug with thread size all too big.

The repair of the mechanical temperature gauges is not as simple as "replace the tube".  You can do this repair yourself if you have access to some basic tools and materials.  I won't elaborate here but you can read up on the basics in the link below.  I have repaired about 1/2 dozen gauges using the method but I substitute dry-ice for the ice/salt bath.
//www.ply33.com/Repair/tempgauge
As mentioned earlier, do not throw out the old gauge.  Sell it or pass it along to someone else if you choose not to repair it.

If you just want to get a drain plug, our host sells them.  Look for part numbers: DAM7335 (standard) and/or DP1 (the extended plug)

Drain plug thread is 5/8 UNC.

See //www.minimania.com/Search_Results/drain%20plug/Parts

I know it's on old thread but I didn't find a replacement for the sensor nor just the drain plug I have been meaning to replace this but I just reused the old bolt but the seal was damaged so the is a leak there. .

So, It's for my Rover Mini Cooper with 1275cc engine. I'm looking for a temperature sensor with the tube to replace. I'm also looking for jus the drain plug, I believe it's 15/16 bolt mentioned earlier by 6464. Where can I find these three items?

Best, Indy

THANKS!

I'll see what I can do.

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YES, the tube is probably leaking.

Cup cake,

Thanks for the advise. Are you saying that both the sensor andthe gauge is working but due to the oil in the tube, it's failing? And replacing to a new tube would make it work again?

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With capilliary (mechanical) temp gauges the tube is filled with a fluid and thats usually what fails. With it hanging down there below the motor I'm not surprized it doesn't work. The tube can be replaced for a typical $150 repair charge. Don't throw out the gauge ... Smiths oil temp gauges are pretty rare and in demand even broken.

Yeah, the plug is in the right side of the transmission. I have a oil temp gauge (is broken btw).

Thanks lads. I will replace it with a new plug. Thanks.

Indy

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You would have to carefully undo the outer-most nut to permit removing just the sender in order to drain the old oil. I say carefully, as you will need to put it back in and have it seal or replace it entirely with a normal drain plug.

You need to find the drain Plug. Facing the engine, it is located on the left side of the tranny. 15/16 bolt. Don't over tighten.

If its the front RIGHT side of the transmission then its the drain plug. The wire is consistent with a mechanical or capilliary type temp. sensor. Do you have an oil temp gauge? 

Hi,

I have a Rover Mini Cooper from 1998 with 1275cc engine. I was going to change the oil this weekend where upon I ran into the surprise not finding the release valve, even though I tripple checked with the Hynes book I have.

The best guess I have found is this:

https://docs.google.com/open?id=0B4iT8A43WftTRkNoSTJIZDdkWEU

It's on the left side at the bottom of the engine. Is this the release valve? If so, what's the item connected to it? Is it the temperature sensor?

Thanks.

Indy