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Just wondering if anyones actually running ATF in their forks as it specifies in the owners & workshop manual?..I read somewhere that some were using Mobil 1 ATF in their GSXRs & other Jap bikes with good results ..the rationale was that Mobil1 was a 7W viscosity & consistent throughout friction/temperature changes..
 

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On the other hand - ATF does work... Maybe not the best - but it's a hell of a lot better than the sludge that came out the first time I did an oil change.

I used it again this time - because I know it works OK, and I didn't want to stuff around 'experimenting' with something 'new' in my bike - just before I set off on a long haul ride. I've had enough shit to deal with as it is.... :( Including (but not limited to) the broken bit in my forks... I'll put it all in a ride report - sometime.

I'll play around with some 10W next time.
 

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It's what we used to use back in the day and it worked great. I once had a bike that kept blowing fork seals, so I put some of that ATF with transmission "stop leak" in it and it never blew another seal.
 

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have used atf on bikes for a number of years without any issues

have also used car oil filters and various other non oem parts
also without any problems
 

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ATF was used "back in the day" because we didn't have fork specific oils to choose from. Use fork oil. No reason not to.
 

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I've used it for years in various bikes with good results. It's way cheaper than designated fork oil, viscosity is consistent, and the additives should extend seal life. More than one companies fork oil is just repackaged trans fluid anyway.
 

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Just wondering if anyones actually running ATF in their forks as it specifies in the owners & workshop manual?..I read somewhere that some were using Mobil 1 ATF in their GSXRs & other Jap bikes with good results ..the rationale was that Mobil1 was a 7W viscosity & consistent throughout friction/temperature changes..
Try it and see what you think. Motor oil can be used too if you like. Why not add a little moly lube as well? Use what you like. Experiment, and when you're done, chances are you'll fiund fork oil works best. I did. :) Try waxing your sliders with pure carnuba wax too. :)
 

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Old Wizard
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Read your Manual to identify the recommended fork hydraulic fluid and then compare its specifications to other fluids in the above Fork Oil Weight Table posted by Chuckracer. The table shows that you can’t choose a hydraulic fluid by what weight is written on the container.

For example, the 916 Service Manual recommends Showa SS08 Fork Oil (cSt @ 40C = 36.8) while the Mobil 1 ATF (St @ 40C = 34.0) has almost the same specs. So Mobil 1 is a good choice for replacing Showa SS08 and there’s no good reason not to use it from a viscosity viewpoint.

If you increase the fork oil weight, you’re using a higher viscosity. This means that you will increase the rebound and compression damping at every click setting.

The only reason to change from the recommended viscosity is if you run out of high (or low) damper settings and you need even more (or less) damping than the maximum (minimum) that the stock weight gives. Quite unlikely.

If you decrease the fork oil weight you'll need to compensate for the reduced oil viscosity by increasing your fork low-speed settings to recover your compression and rebound damping. However, now you’ll have less high-speed damping than the fork manufacturer and Ducati engineering intended because high-speed damping is controlled by the flow rate through the internal shim stack and unaffected by damper click settings.
 

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I've used it for years in various bikes with good results. It's way cheaper than designated fork oil, viscosity is consistent, and the additives should extend seal life. More than one companies fork oil is just repackaged trans fluid anyway.
I'm open to saving a few bucks any way I can. I just had a look for myself into this possibility of a cheaper alternative. A one liter bottle of the BelRay fork oil I used for my ST at the start of the season, which was enough for both stations with some left over, goes for around $10.00. The Mobile 1 ATF Shazaam mentioned is around the same price for a QT. You can buy cheaper ATF fluid and cheaper fork oil. You can also find more expensive of each. If it works for you, use it. I don't see the benefit personally. Seal longevity? I guess, but if I'm pulling my forks apart for service, there is no reason to not change the seals at the same time. These things are dirt cheap, especially when one considers what folks here will spend for a billet clutch pressure plate, or levers, or...

Also, the old saying regarding suspension is "the best you know is the best you've ridden". You might find proper (more than just a viscosity question) fork oil will give you better performance. But who knows? I haven't tried ATF for myself in my Ducati forks.

Edit: Regarding fork service. Yes, I know, you can just dump the oil and replace it without pulling the forks apart. When I do service, however, I also use a little seal grease (Race tech brand) on the bushings and on the fork seals. This makes a notable difference in performance. That alone is worth the cost and effort of disassembly!
 

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Back in the day I worked as an analyst in a quality control lab for Gulf Oil. One night I took samples of all the fork oils I had on hand, about 5 or 6 of the major brands, and some gas station brand ATF to work and tested them to compare viscosities. I ran them at 40 and 100 degc. I don't have the exact data any more but I found that the ATF lost very little viscosity at the higher temp. As good or better than all the oils I tested. I know some of the very expensive oils designed for shocks and the lighter "01" fork oils available now are better but I feel that on a street bike you'll never gets forks hot enough to matter. Forks on street bikes just don't get hot.

Edit: I do remember that the absolute worst of the bunch was this stuff called Kal-gard, or something like that. It looked like chocolate milk as was suppose to contain moly. I never used that stuff again. :)
 

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The down side of ATF is the plasticizers in it that will cause fork seals to swell and then stick and the different lubricating properties. I’m all for saving a buck, but not on a set of $2k forks. IMHO.
 

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The down side of ATF is the plasticizers in it that will cause fork seals to swell and then stick and the different lubricating properties. I’m all for saving a buck, but not on a set of $2k forks. IMHO.
You can use whatever makes you feel good but do you really think your owners manual would tell you to use something that the fork seals were not compatible with?

 

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Old Wizard
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Manufacturer Recommendations

You can use whatever makes you feel good but do you really think your owners manual would tell you to use something that the fork seals were not compatible with?
I agree. It’s probably wise to let the fork manufacturer be the final arbiter of what formulation of hydraulic fluid should be used in their product.

Rubber seals and o-rings used in automatic transmissions contain plasticizers which make seals soft and pliable. Plasticizers normally contribute between four and seven percent to the volume of rubber seals. Hot transmission fluid can remove plasticizers from seals and o-rings, causing them to become hard and brittle. Removing plasticizers can also causes seals to shrink allowing transmission fluid to leak.

The manufacturers of ATF know all about this and formulate their products to be compatible with common seal materials used in transmissions.

Ohlins and Showa are also aware of material compatibility issues and have extensively tested their fork seals with the hydraulic fluid they have specified in the Ducati Manuals. This is not to say that fork oil from another manufacturer will result in damage to the fork seals, they simply haven’t been tested by the fork manufacturers for long term compatibility with their particular seal material.
 

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You can use whatever makes you feel good but do you really think your owners manual would tell you to use something that the fork seals were not compatible with?

I tried 7.5 ATF in my ST3 forks when I dropped in stiffer springs and a RT comp damper kit, and it sucked, *still* felt way too harsh. Switched to 5W fork oil, and the forks work/feel much, much better.

Ducati also changes what they recommend from time to time too, and besides, they also recommend high octane fuel and I use regular, a certain vicosity oil for certain temps and I choose my own based on shifting qualities, in other words I use the fluids I feel work best for me based on *my* experience, not on what Ducati says. Those manual recommendations are merely "product placement" ads for sponsors IMO. :)

Their track record on recommneded coolant hasn't beem too good lately. :(
 

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According to James Siddall at Superplush Suspension, most cartridge forks regardless of brand are designed to work with a 5 wt. oil and moving away from that can create as many problems as it solves, so if you need more rebound or compression than your fork has, you need to re-valve, not go to a thicker oil.
Thicker oils can cause cavitation resulting in un-even and inconsistent response.
 

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I tried 7.5 ATF in my ST3 forks when I dropped in stiffer springs and a RT comp damper kit, and it sucked, *still* felt way too harsh. Switched to 5W fork oil, and the forks work/feel much, much better.

Ducati also changes what they recommend from time to time too, and besides, they also recommend high octane fuel and I use regular, a certain vicosity oil for certain temps and I choose my own based on shifting qualities, in other words I use the fluids I feel work best for me based on *my* experience, not on what Ducati says. Those manual recommendations are merely "product placement" ads for sponsors IMO. :)

Their track record on recommneded coolant hasn't beem too good lately. :(
The reason I did the test I did ( about 30 years ago ) was to determine actual viscosity because I was getting fed up with the advertised ratings not working out as advertised. I wasn't trying to find anything magic. It's just that I found the advertised 5wt or 7wt or 15wt rating wasn't consistent and had me chasing my tail. The only reason I quoted the manual was to point out that ATF in general isn't going to cause your seals to fail. The 7wt viscosity of ATF is very consistent from brand to brand. If that happens to give you the viscosity you need it's an option and not a bad one.


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