Fork oil or suspension fluid

[Pigeonroost]

There is another topic going on here now about fork springs and shocks and they got to discussing fork oil.  There was mention of using 20W or 30W???  I did not want to hi-jack that thread, so I am asking here.  Are folks using motor oil in the front suspension?  I can see how such heavy oils could provide increased dampening with the damper rod design, but seems like maybe over-kill to me.  The heaviest fork oils I have encountered are 15w like BelRay or such.  We used to use ATF which is probably about 5w to 10w.  Cartridge forks generally use 5w to 10w.

I looked in the WIKI and came up empty.  What is the scoop on these heavier oils in the fork tubes.

prs

[The Buddha]

I have seen 20, not more than that I dont think.
I guess you can use motor oil but what weight and I dont think that 20/50 will work. I suspect its just high detergent motor oil.
Maybe it will, cos it never gets warm enough to work like the 50. It works like the 20. But is that 20 the same as the 20 of 20W fork oil ... no clue.
Cool.
Buddha.