Depends on your fork setup, rider weight and your riding ability. Fork oil is available from 5 wt (thin oil = quick action) to 30 wt (heavy = slower action)
use 15wt or 20 wt fork oil and add 259mm per fork for an 1979 gs1000s
5 wt.
533ml of 10 wt
11.6 oz 15 wt for my 05
110 ml per leg . i found 5wt - 7.5 wt works best
IF it is virgin olive oil it will be fine.
7 inches measured from the top of the collapsed tube with spring out 10 wt fluid, same measurement as for the 1100
depending on rider weight of approximately 170lbs use 10wt suspension fluid or fork oil if that's all you can find. rider weight less than 170 lbs use 7.5 wt. or over 190 lbs use 15wt.
The oil to use in a 2002 Montana depends on the climate. In summer, use a 10-40 wt oil. In the winter, a 10-30 wt or even a 5-30 wt is alright.
always use 5x30
30 wt oil