I have just replaced my front brake pads, i want to change the brake fluid, i managed to release the right bleed nipple, but the left one is soid, it has been rounded slightly by a previous owner, so i thought i would try and drill out the nipple and replace it, i looked on amazon but there is M8 and M10 nipples, does anyone know what size I would need,

 

I'm about 90% sure it's 8mm.
That the size of the wrench used to loosen it and I believe also the thread size 8mmx1.25.
If you're going to get new nipples, think about a set of speed bleeders.

Don't drill out the old nipple, that's the hard way to do it.
Find a nail just slightly smaller diameter than the nipple inside.
Cut it off slightly longer than the nipple.
Then use a hammer to lightly hit the end of the nail until it's flush with the end of the nipple.
This will cause the nail to flair inside the nipple and make it solid.
This prevents the nipple from breaking off.
Now use a pair of vise gripe, to remove the nipple in one piece.
This is the simplest and safest way I've ever found to remove stuck nipples.

 

Cheers Phil , I appreciate all your help,

 

well thanks to your help phil, I got it done, I ordered a butane blow torch from amazon £10.00, I done what you said hammer a oversize nail in the nipple, got a bit of heat on it,then used a smaller socket 7mm,knocked it on with a hammer as the nipple had started rounding off,then to get some leverage on it i mounted the caliper on the bike and used a bar on the socket, easy,thank you. I am waiting for a seal kit to arrive, I will replace seals and rubber boots,i am also painting the calipers blue and I will replace the brake lines with blue braided lines, i would like to change the fluid reservoir but not sure what one would fit,