We tackled this job today on a Club Member's car - thanks to M/A for the writeup and pics too.
The OEM oil line has a swedged fitting and an o-ring seal - the rubber o-ring gets dried out from the turbo's heat and after a while the line leaks. We used the Detroit Tuned kit, but I think it's a good idea to also replace the turbo to downpipe gasket (ours was blown out) and the nuts and studs that hold the downpipe to the turbo. New studs from MINI are quite a bit shorter than the originals.
The first thing to do is remove the top shield, the lower bolt on the left only has to be loosened, (you can't get it out anyway) as the hole is a slot so the shield can lift straight up off of the bolt. There are 6 bolts that hold the top shield on. It's difficult to get the shield out from under the various bosses on the head, but if you fiddle with it it will come out. The lower shield is held on with only four bolts, finding them is the hard part here! You really can't remove the lower shield out of the car till after the downpipe is out. To get the downpipe out you pretty much need to remove the studs out of the turbo, there just isn't room to get it out otherwise. The top stud galled coming out, but fortunately it only destroyed the stud - a good tap run into the hole in the turbo cleaned the threads right up and the new stud went in with no issues.
The clamp on the lower part of the downpipe can be a challenge too, it's SS and very stiff, and you have to expand it over the joint - take it to the rear rather than onto the downpipe, it will be much easier to reinstall if you do.
The only other difficult part is figuring out which of the 400 types MINI uses hold the 02 sensor wire clips together - the upper one is a tab on the side that you push in while pulling out the plug, the lower one has a red cap that you pull out to release the plug.
You also have to remove the turbo support brace and the inner shield that bolts to the block to uncover the line. BTW, DT says take the old line out the top, we found it much easier to get it out the bottom. When installing the new line, do the bottom first, the lay the line in the right place before installing the top banjo bolt and tightening the compression fitting.
I took a couple of pics to show what I mean.....
Here we have the top shield off, you can see the gasket has blown out and the old leaky oil line. Also, the top stud has galled in the turbo itself. I managed to get it out by double nutting it and working it back and forth and backing it out a little at a time till it came out.
I can see how the dealership charges $800 to do this job (the new OEM line is $100 of that) - but comes with a little clip on shiled to keep the heat off the swedged end of the line.
Here's the bad stud, and the other two cleaned up to go back in...
Here you can see the new oil line installed and the new shorter OEM stud. The big hole is for the 02 sensor.