I work in an Automatic Transmission Plant, and I asked the same question the other day. Apparently the Dexron type fluid that is usded has a poor viscosity index, and can attack seals. I'm sticking to proper fork oil!
It doesn't attack all materials. The seals in our transmission are all suitable for the fluid. However I'm not sure if those in forks are. I'll quiz the guy at work again as he seemed to know what he was on about.
Jeremy has worked with the engineers at Mobil for quite a long time before they came up with Mobil 1 ATF. He had a very demanding list of requirements that he needed for a suitable suspension fluid.
After alot of testing Mobil ATF 1 proved its' worth.
Take Care, John
Uh oh, I'm starting to think I jumped in too early here :(
By ATF are you guys reffering to Automatic Transmission Fluid? Which is something I have heard can be used in forks.
I can't help feeling that I seem to have offended members in this forum for trying to post information that I thought may be relevant. I wasn't trying to step on anyones toes. In my defence I did list what type of Transmission fluid I was speaking of.
I have used ATF in forks on a couple of bikes ever since I was redoing the front end of my Honda VFR and the shop manual said ATF could be used. I was putting a set of Race Tec emulator valves. I called them up and they said that would be fine. I had some on the shelf and used it. I used it in two dirt bikes after that and never had any trouble. I belive it has some sort of seal conditioner in it, as auto tranies have about 2 million small seals in them. I have put it in the gear box of 2 stroke bikes that were a bit leaky and it seamed to swell the seals up and not leak as bad a even 90 W gear oil. Smell better too! :)