Firstly, I know tht Yozuri Ultrasoft is probably the best to use for spinning reels, but this is what I have.

I have a Shimano Saros 2500 it's rated for 140 yd of 8 lb line.  Will 8 lb CXX work or will it get more line kinks when used on a spinning reel?  I have 6 lb CXX spooled on right now, but looking to go w/ a heavier line.

If I do use 8 lb CXX, I'll spray the line on the spool w/ Reel Magic.

ghost ,,, the cxx is a great line tough as heck ... but i can tell you its not the best choice for spinning gear ....  for spinning gear id recomened eighter p-line cx or p-line flourclear .... i prefer the flour clear ... 8lb would be great ...  

Dont use CXX on the spinning reel. You are asking for a world of trouble and headaches. I have tried it, my friend has tried it and we had so many issues it wasnt funny. With my Baitcasters I have had no problems (except for memory issues). Go figure :-?

Pline CX Premium in 8# is an excellent choice for spinning gear.

6 or 8 lb. CXX is fine on spinning reels.  CX is better suited for the application, but CXX will not cause any trouble.

Funny you ask; I have 8lb CXX spooled on my IMX SJR 723.  I tore'em up yesterday and today throwing finesse jigs, flukes, and creatures using only my 6' spinning rod.  I couldn't have been happier; no issues to speak of.  

Haven't used 8# CXX, but have used 10# CXX on spinning reels without any problem.  

CX is definitely more limp and handles better on spinning tackle. It's all I use on spinning reels.

Before you respool and even afterwards try using KVD Line & Lure Conditioner on your P-line.  It will take most the stiffness/wiryness out of the line much better then Reel Magic.  It will make your casting longer and more accurate too.  Check out the threads on it here on the forum.

I use it with no problems.