Converting from dot 4 to dot 5.1 brake fluid -Procedure?

[Mustang]

What is the procedure for this?
Is it just a case of start bleeding the system in the noraml way, top up with 5.1 and try to flush the dot 4 out that way?
Or do you need to use a pressurised system to flush out all the dot 4 (probably creating an air lock) before you can start to add in the 5.1.
Or some other approach?
I ask this because I've read that mixing disimmilar fluids in the reservoir can damage the seals, etc.
Any help appreciated.

[CJ]

I ask this because I've read that mixing disimmilar fluids in the reservoir can damage the seals, etc.

Correct. You would be as well to buy some brake fluid flush and run it thru the system, drain the existing fluid down to the min point in the reservoir without emptying it completly and then fill up with flush. You'll probably have to do this twice and then the same again with the new fluid. It would be advisable to have 1.5L of fluid on hand as bleeding can use a bit, especially if you have air trapped in the lines. Basic brake bleeding kits are relatively inexpensive at the local factors. Remember to bleed in the right sequence!

CJ

[Mustang]

Thanks CJ, I was not aware that a flusing fluid was available.