How often do you change fork oil?

I've also wondered about the difference in oxidation between atf and fork oil. I fella once told me if you can smeel the oil, change it...
I feel that if you can smell the oil (through the bleed holes) then it way past time for it to have been changed. I'm not real sure what oxidized atf smells like.
I would think a change mid-season would be the ticket.

Funny story about the Mobile ATF. I called them directly to find out what the equivalent weight of it was. HEre is how it went:

Matt - Hi, I am calling about your Mobile 1 ATF product. People use it for suspenion fluid in motorcycle forks. I was wondering what the equivalent weight would be.

Mobile -- no they dont

Matt - yes they do sir

Mobile - ATF does not have a weight and it not used in motorcycles

Matt - never mind, bye

So I called our distributor for it, he said about 10-15w. Also since ATF has a lot of detergents to not use that on old seals. Be sure to have fresh fork seals.

As far as when to change it, depends on the riding you do really. I change mine at beginning of the season and usually about mid way through. I use the Amsoil fluids in there and have not had a bike long enough lately beyond that. So the second time is like 1 month later (shortened riding season in the local mountain cause of fire dangers) which is more like a flush to get the rest of the old fluid out.

Mr. fred:

Even for someone that greases his suspension linkage every 400 miles (hey...it COULD be KLICKS..kilometers that is), twice a year on the front and once a year on the back should be sufficient. :)

My R5 manual said to decarbon the head every 1000k. I got around to mine at 43,000.......MILES! They were pretty clean!!