Urgh typical. Few months back I changed all the ball joints on the front end, and also replaced the axle oil seals and CV joints.

While investigating my shit brakes, I found this:

https://photos.app.goo.gl/VAGcqjiidzjs6neX8

Looks like the axle oil seal on that side has failed pretty badly... Which makes me concerned as they were genuine seals, not cheap shite. Either I've somehow installed it incorrectly or theres something going on with the ball joint adjustment collet thingy that's ruined the new seal rapidly.

I’ve changed quite a few ball joints and not had any problems with the collet, it always seems to be pretty rusted in and unmovable, how did you put the seal in, I only ever just push it in with my thumbs, never had any leak

When i had mine apart for the Balljoints and the wheel bearing on the nearside, there was a leak as well. Seal seemed fine, but wheel bearing was completely shot to hell. Not actually noticable by noise etc, only picked up on MOT. After replacing the wheel bearing (there was detectable play at the wheel beyond the balljoints) the leak stopped. Didn't need to replace the seal.

That side had a new bearing at the same time as all the balljoint work. The other bearing felt fine so i left it.

I guess i should check the bearing for play!

Seal was tapped in gently with a large socket.

One of the collets was rusted solid, but the other one, i think on this side, went loose when i removed the balljoint. I was careful not to turn it, but i do remember thinking "thats a bit wobbly" and realising it was actually in two parts, which i guess wedge out against the thread when the balljoint is tightened.

Also check there isn't any signs of wear on the driveshaft where the seal goes, though with a new seal even a bit of wear shouldn't allow it to leak. Collets on mine didn't move either. As said above the bearing on mine was in a right state, but not really obvious until it was lifted up on the mot ramp, where there was clearly vertical play in it (wouldn't have been noticeable for the play in the balljoints anyway whilst driving)