Originally Posted by vinniekq2
NOTE: I would use brake fluid rather than oil or cleans the finished piece before installing as oil is not compatible with the seals in the calipers/wheel cylinders
2) most buttons or tools/ have a line on then to show how much line needs to be outside of the clamp
Very little oil is used, and virtually none of it ends up inside the tube, so the seals should be fine. I usually flush a good bit when bleeding a new system anyhow to insure any debris is removed.
My own flaring tool used the thickness of the side of the button (others may have a line), but I found mine works with better just slightly more than that. I guess I should have said to experiment while practicing to see if slightly more or less yields a better flare.