Fork Oil suggestions

[Big IV]

I bought my Valk in January a few years back. It was the first time it had ever been out in the cold on the ride home. It also had never been out in the rain or really ridden at all. So that spring I replaced the fork seals and put in new fluids.

It has now occurred to me that I haven't changed the fluid since. The seals are still holding and I proceeded to forget about it. (I replaced my XS11 fork fluids nearly annually but only when the seals let go and it started leaking).

It's time to replace the fork oil (and then some). What is called for and what is recommended?

I keep meaning to look it up in the manual, but I keep forgetting.

Thanks for the advice.

[PAVALKER]

Medium fork oil.  I used AMSOIL Medium.  Progressive recommends a 15w shock oil, but I just added a pinch more (1/8") to the measurement method.