To be honest I use it every day and would say black lane..
I was under the impression it was left lane for first 2 junctions and right for others after that, given there is more than 4 exits on this one I assume that the first 3 would be black and the remainder red.... although as a rule, assumption is the mother of all ****up's !!!
Also, if the traffic is busy which it usually is then I use the red lane and nip out in front, for which a lot of you will probably want to shoot me for but when i'm driving 74 miles a day to lytham and back i need to crack on....
Cheers
Lee