I agree with Skids on the Ohlins springs too
but, on my (Snot) M600 forks - reworked, I use 5w full synthetic competition oil, like MX type, which seemed to work really well. But these are Showa forks.
Andy was very happy with them, particularly after we added shims to pre-load the springs a bit more at the first meeting at Cadwell. You can see how he did from the 1st 2 races results(no 36) ...and rides at 13 stone fully kitted out.
Alan