I couldn't find it in manual, I'll try again tomorrow.
I replaced one rear shock, bought one from ebay, it looked like it lost all oil.
And I need to change oil in forks. Lucky me, they have drain bolts!
thanks.

 

10 weight should do. That's what's in my forks now. I might mix it heaver next time. Think it's been mentioned on here that 10w is good for shocks.

 

Lots of folks are going to tell you something like 10 wt, 20 wt, whatever, but the problem is that doesn't mean a whole lot because lots of oils, dare I say most, are not labeled to be exactly what wt your getting. Meaning it may say 10 wt on the bottle but the actual oil could be far from 10 wt. For me, I tried to narrow it down to viscosity at 100C, which for me something around 7 works. As luck would have it that's what the Showa SS8 fork oil measures out to, as does Valvoline Dexron III, as does Mobil 1 Syn ATF. The latter is what I use, works great for forks, shocks, and primary. YMMV.

 

Somewhere around HDF there is a thread proving your point, where someone has tested viscosity of fork oils and recorded the actual results by brand. Best to try a well known brand and if their oil doesn't give the desired results use a different grade of the same brand.