FORK OIL

[VSTAR650]

Hello All,
Just curious, has any body here used something other than fork oil in their forks, ie. transmission fluid, hydraulic fluid, multi viscosity motor oil, etc...?????

 

[Brybo86]

I haven't but many forums suggest M1 ATF is a very similar weight

 

[Andy636]

Originally Posted By: Brybo86
I haven't but many forums suggest M1 ATF is a very similar weight


And what weight might that be since fork oil come in different weight? Depending on application you can have 2.5, 3, 3.5, 4.25, 7, 10, 15 and 20

@VSTAR650 why would you want to use some other fluid when fork oil is specially fpormulated for that and it's cheap

 

[Astro14]

When I used to ride an MX bike, the fork oils had special additives to prevent foaming, while ATF and motor oil have those, I wouldn't be certain there was enough present to prevent foaming, and the loss of damping, in hard use....

Actual fork oil, in 5W or in 10 W, wasn't that expensive, IIRC, and I would use the product formulated for that application, rather than risk poor performance with a substitute...

Of course, if the bike in question is a cruiser....maybe it doesn't get the workout that my Suzuki did....and maybe it doesn't matter...

What viscosity does this machine specify? How much do you need?

 

[tom slick]

Fork oil is about the same price as synthetic motor oil and synthetic ATF why bother trying to substitute? You rarely change it.

 

[BusyLittleShop]

Back in the 70s BelRay Fork Oil bottles were printed with the words SAE 5 Mil-H-5606 as a 5wt oil for rear shocks... the only trouble was Mil-H-5606 was USAF hydraulic fluid and not for sale...

 

[outdoorsman310]

i just bought fork oil. i think bel ray

 

[Silk]

I've been using ATF forever, never had a problem with it, off road and road bikes. I have used fork oil at times, but don't notice any difference to ATF. I've always got ATF at home, if I haven't, I can get it 24/7 at the servo, bike shops here aren't 24/7.

 

[Cujet]

I started using M1 ATF in my dirt bike forks and shocks, that way the fluid viscosity and properties were consistent. I then valved the shocks to my liking. I was able to tune the suspension perfectly. (Honda/Showa components)

 

[Rob_W]

I've used several brands and weights of fork oil in my various MX bikes. For now the best I've used has been Motorex 2.5 wt. it's not the cheapest but my forks are always very plush.

 

[Ken2]

ATF is very close in viscosity to 10 wt. fork oil. It works well. The newer low vis ATFs such as Dexron-VI with have slightly less damping.

Always start with the viscosity shown in your owner's manual for your forks unless they've been modified. The size of the air pocket in the top is important--fill with the volume specified.

Note that the "weights" of fork oil vary by the brand. Not all so-called 10 weight, for example, have the same actual viscosity. It would have been better if they'd all use the ISO viscosity grade at 40°C like other hydraulic oils use, but they don't.
http://www.hrpworld.com/client_images/ecommerce/client_39/products/pdf_3119_1.pdf

 

[Cardenio327]

The Honda Service Manual for my 400 cc says to use ATF. When I changed the fluid over a year ago I used Mobil 1 ATF. As Ken2 mentioned above having the same volume of fluid in each shock is more important.