Rebuilding a rear shock, 3wt shock oil vs 5wt fork oil..

[OldNo437]

So I need to rebuild my rear shock, it calls for 3wt shock oil, but for whatever reason thats hard to find locally... theres 5wt fork oil all over the place.. so whats the diff? I know it will be thicker, so it will be slightly harsher, but has anyone run 5wt fork oil in their rear shock? whats the effects? thanks!

[BOB MARLIN]

I use ATF when I do a rear shock (350x). You kinda have to assemble it while its submerged in oil to make sure you have no air in it. Having enough shock oil to do it this way would cost a small fortune. The results have a stock feel to it.
If you want to use light shock oil you can get 2.5wt at a Yamaha dealer. I forget what they call it- S1 or something like that. Its whats called for on some of the YZ's and WR's.