I tried the 2.5 weight oil as recommended by a local suspension guy.
He set it at 150 mm. I personally didn't like it. I remember ArmPump recommending 7.5 weight to someone on the other site a couple monthes ago, so I tried that at the same 150 mm. I liked the 7.5 better, the front tire stayed planted better in the turns.
Since you are a little bigger than I am, you would probably get better results with the 7.5 or even 10 weight. BTW, I only used synthetic. Several non-synthetic 5 weights are heavier than synthetic 10 weights. Don't switch brands when trying different weights.
Call me if you are going to ride Bartlett or Four Peaks/Sycamore this weekend.