DOT 5 brake fluid problem

[karl_mh]

Ive just completed the modification of my braided brake lines to fit a newly installed Satchshift hydraulic handbrake, prior to me getting my hands on the car the brake lines were already primed with brake fluid. During the brake line mods I've had to drain the fluid and I'm now at the point of replenishing the lost fluid, however, after further investigation I've discovered that the fluid is what I think is DOT 5.

Anyone out there a brake fluid oracle?

Based on what information I can find on the inter web it seems the DOT 5 is purple in colour - this appears to be the same colour as mine.

From what I can gather, you can't mix DOT 3, 4 or 5.1 with DOT 5 "they say" its not really used as a performance braking fluid unlike DOT 4 so this now poses a problem......is it possible to completely flush out the DOT 5 and replace it with DOT 4 without any adverse effects to the braking system / seals? I've read some horror stories about mixing the two, anyone had the same issues.

Others also say that the pedal can get a little spongy which in my book is never good.