fork oil substitute

Does anyone know whether automatic transnission fluid can be a satisfactory substitute for fork oil ? I was
changing fork seals today and and dumped about 6 oz.+- of what looked like atf from each tube.

 

ATF is a good substitute for fork oil due to its anti-foaming properties. Many motorcycles used to specify ATF for the forks as stock. ATF is roughly equivalent to 7.5 weight fork oil, so will be a bit on the light side for any of the XJ series, but you might find it to be acceptable.

 

Second that.
I've only ever bought one bottle of fork oil in my life, about 20 years ago. That only got used because I came across it in a box, recently. All the other times I've replaced fork oil I've used ATF or an ATF/ motor oil mix, according to the specs that used to be in the maker's manuals.
The XJ9 has had a recent fork oil change and is currently filled with 5W40 synth engine oil, and handles fine.

 

I'd caution against using motor oil alone in forks, particularly on anything ridden in a sporting manner. It will tend to foam up, and you will not be happy with the sudden lack of damping. Been there- done that; not going back.

 

Been using it for years and it's never been a problem. I'm keeping an eye on the XJ with the synth in, because I'm curious what it might do in the cold.
Then again, I don't ride around like a GP star or expect too much of lardy old suspension, so who knows. Perhaps more demanding riders might find it lacking.

 

Rather than motor oil use hydraulic fluid. It has the right additive package to protect seals and the anti-oxidants work at low temperatures.

 

Well, there's an idea. I'm in the middle of farming country and hyd oil is common enough and cheaply got.

 

Can those in the know point us that are not in the know (like me!) at a suitable product to fill the tubes? (Brand/Kind, etc?) Something perhaps that can easily be found at a Pep Boys or Advance Auto Parts?

Are we talking about something like this?
https://www.pepboys.com/product/details/9189304/00177

Thanks.

 

Ideally you will use an oil that is meant for forks. Motorcycle dealerships have it in stock. Most of us find that a 15 weight fork oil is just about right for daily all-purpose riding.
If you choose to use ATF or hydraulic fluid (which is about 7.5 weight (too thin in my opinion)) then any brand will do. While I am a certified, card-carrying cheap bastard; I prefer to use fork oil in my forks.

The oil has two main jobs; lubricate the moving parts to prevent premature wear, and control the action of the fork so the front tire stays in contact with the road as much as physically possible. If you have too thin of an oil in your forks (the correct thickenss will depend on the weight of the bike, your weight, and how you like your ride to feel) the front tire can bounce around enough that the motorcycle becomes dangerous to ride (the same is true of going too thick as you'll effectively hydrolock the forks, but that requires some really thick oil).

 

Like k-moe said earlier, automatic trans fluid will work but lighter weight (7.5w) than that recommended for the XJ700 (10w). If you are just an easy rider it will probably be fine. I just replaced the seals in mine and it had less than 1/2 the required amount of oil and I had been riding it for a couple of years since a mechanic supposedly changed the seals and replaced the oil. With the proper amount of oil I have a much firmer ride. I suspect that 7.5w ATF would be better than what I was riding on. In any case, I got a quart of fork oil from the local Honda dealer. A little expensive, $14, but at least I know it's the right stuff.

 

Haynes book says 10w/30 motor oil or 10w fork oil except 750rh/rj takes 20w fork oil

 

I ran 20wt fork oil in my 750 for a year. 15wt is more better for me, even with luggage. Fork oil specs are meant as baseline suggestions.

 

Now I'm really feeling like i'm lacking oil in my tubes. This is my first time, full time bike, so I don't have any other experience to compare it to. At the very least, I'm going to do a drain and refill as the service manual instructs.

 

now you're talking. it doesn't have to be perfect, just better.
watch out though, that oil can squirt out pretty far when you bounce the front end and can be real stinky