Interesting tidbit

[Dogma]

Razor..then the engineers that wrote the service manual stating the 50/50 mix are all wrong then and suggest using what will quickly deteriorate the fork seals....right?

Hang on, they were writing about ATF and engine oil from around 1980. Have there been relevant changes to these since then?

[chuck hahn]

its clearly stated in the 77 750 service manual..thats where i first learned of this formula..and i also suspect its in manuals for even older bikes than mine. I dont know the differences in PRE 80s ATF and oils though.,,as far as when they started the whole friction additive / friction reducer stuff.

[rustybronco]

Dale, sure there have been changes in oils since the 80's, both in engine, fork and shock oils, but does that make the original ATF/engine oil suggestion no less valid than when it was first issued?

[chuck hahn]

Whats the input and tail seals on automatic trannys made of?? I dont really think the ATF will break down or damage any fork seals.

[razor02097]

Razor..then the engineers that wrote the service manual stating the 50/50 mix are all wrong then and suggest using what will quickly deteriorate the fork seals....right?

I never said the mix was wrong. I said I don't know why someone would go through the trouble when fork oil is available ready to pour and in any viscosity you want and not that much more money.

[chuck hahn]

Post 13...atf isnt kind to all rubber seals.

[razor02097]

Post 13...atf isnt kind to all rubber seals.

Personal experience ATF+4 swelled the seals out of a part I was soaking. In that instance I was using ATF as a degreaser. Maybe dex/merc is better?

I wouldn't use ATF in something unless I knew it wouldn't damage that part. That's just me though.

[chuck hahn]

Seals on a fork shouldnt swell out as they are held in with retainer clips..did the +4 noticably soften any of the rubber..like make it sticky or something? if thats the case..then that gives me a clearer picture of the nature of the post..maybe the +4 is something to stay away from???

[JJ]

I was told to use Dexron II ATF, but the present designation is Dexron VI, and have successfully used Mercon V without much noticable difference. It feels like Mercon V may be a slightly higher viscosity.

I think I am going to try 20wt fork oil when I replace the fork seals on my XJ650 next month and see if there's much of a difference.

[razor02097]

Seals on a fork shouldnt swell out as they are held in with retainer clips..did the +4 noticably soften any of the rubber..like make it sticky or something? if thats the case..then that gives me a clearer picture of the nature of the post..maybe the +4 is something to stay away from???

the seals were actually swollen about 2X normal size. They were slippery and very soft. I ended up replacing all the seals and orings. I own a Jeep so I had ATF+4 on hand. I wish I saved the old seals from my forks... would be a great experiment to try. I don't know what the seals on the caliper were made of but they should have been chemical resistant because they are exposed to brake fluid... Maybe the fork seals is a different rubber.

[chuck hahn]

HMM.. Place a seal in +4 and one in another for the same amount of time and then compare. Should be very telling.

[first timer]

Keep in mind the factory book was write 30+ years ago, that's a long time. Back then I bet there weren't many oils out there for forks that's why they say use atf. Go open up a new factory manual they all say use fork oil. Even a GZ250 which runs super basic damper rod forks like the GS; the Factory manual sez to use fork oil not atf.

The manual info is just out of date. Just like cigarettes don't cause cancer... I am sure atf works most people won't notice a difference if you are just puting around but if you are a serious rider that makes these gs work hard why not just run fork oil, it's not that expensive 3 or 4 dollars more then aft.

if you are that cheap maybe riding bikes isn't for you..