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adaguy

My review: Mobil 1 trans fluid in 2006 forks, with a suprise finding

18 posts in this topic

Disclaimer: I am not an engineer nor is the following review based upon a double blind placebo test. However I am a good wrench and explorer willing to share my experiences whether right or wrong.

After my curiosity got the best of me, I decided to use Mobil 1 synthetic transmission fluid in the outer chamber of my forks and I used maxima 5wt in the inner chamber.

I came to the conclusion that the two chambers would not mix. Well apparently they do share or mix somehow.

The Maxima is very translucent light blue oil and as you all know the trans fluid is red. After about 20 hours I decided to change the fluid. Guess what color the inner chamber was……..Yep, it was red. Yah weird?

How did the forks perform? You ask? They were amazing but I need to throw in a wrench.

Upon inspection of my fork bushings they didn’t have wear but had a weird bumpy puffiness about them, almost like a chemical reaction with the Teflon. I cleaned the bushings and let them set, the puffiness settled down and the bushings looked normal after 24 hours (I replaced the bushings anyway for those wondering).

My conclusion: the trans fluid isn’t compatible with the Teflon coating on the bushings and there is a sharing of oil between the outer and inner chambers. That being said, the forks worked very well despite my findings.

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Hmmmm. If you have an oil height of 70mm in the outter chamber before you ride the bike, shouldn't you be able to then measure how much is in the outter chamber after a ride and see that there is still infact an oil height of 70mm in the outters? This brings me to the second question, if the oil does infact mix (and there was nothing wrong with your forks), then how does the oil height in the outter chamber remain the same?

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I didnt check the amount of oil when I tore them down but I appreciate your logic.

Bottom line is, the inner chamber oil turned as red as the outer chamber.

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If you have an oil height of 70mm in the outter chamber before you ride the bike, shouldn't you be able to then measure how much is in the outter chamber after a ride and see that there is still infact an oil height of 70mm in the outters? This brings me to the second question, if the oil does infact mix (and there was nothing wrong with your forks), then how does the oil height in the outter chamber remain the same?
First, the outer chamber oil level in the '06 fork is not set by fluid level, but by volume. You could of course, fill it with the prescribed 355cc, then measure it to establish what the oil level should be, if you wanted to.

Secondly, the inner chamber, when properly assembled will hold no more oil than it was filled with in the first place, except for the small amount that may be exhausted from the inner chamber as it heats up. It may be able to draw this back in once cooled down, but it seems unlikely. Even if it did, the total amount of oil in the fork can't really change.

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First, the outer chamber oil level in the '06 fork is not set by fluid level, but by volume. You could of course, fill it with the prescribed 355cc, then measure it to establish what the oil level should be, if you wanted to.

Secondly, the inner chamber, when properly assembled will hold no more oil than it was filled with in the first place, except for the small amount that may be exhausted from the inner chamber as it heats up. It may be able to draw this back in once cooled down, but it seems unlikely. Even if it did, the total amount of oil in the fork can't really change.

Your second point answers the question. Assuming the inner chamber keeps its oil at the same amount, and assuming the oil does infact mix, the outters will simply just take the excess oil (which is whatever volume you put in when assembling the fork). Makes sense

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In theory, they shouldn't mix. The inner cartridge is filled completely full on assembly, and is sealed. However, as I said, if it were to heat and expand, the same blowoff that occurs when you assemble them could release a small amount more. This oil should be gone from the cartridge forever, but it's possible that the small vacuum formed by this lowering of the IC oil level and the oil cooling off could pull some OC oil past the shaft seal. It's not supposed to, but it could.

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Grayracer,

Interesting theories…more food for thought, this is how Mobil-1 stacks up to some other suspension fluids. (Lightest to heaviest)

Yamaha 01 Fork Oil (Kayaba)

-Viscosity Index = 96.00

-Reported cSt @ 40C (CentiStokes)=15.60

-Reported cSt @ 100C (CentiStokes)=3.45

Race Tech Medium US2 (Motorex)

-Viscosity Index = 192

-Reported cSt @ 40C (CentiStokes)=32.9

-Reported cSt @ 100C (CentiStokes)=7.2

Mobil 1 Synthetic ATF

-Viscosity Index = 202

-Reported cSt @ 40C (CentiStokes)=34

-Reported cSt @ 100C (CentiStokes)=7.60

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The '06 fork calls for Yamaha Suspension Fluid S1, which is a bizarre fluid, if you've ever actually seen it. Most of the suspension guys I've talked to don't like the KYB fluids much, and they're very pricey, anyway.

Hydraulic suspension fluids don't always equate well to SAE viscosities, and in fact, they don't always even put it on the label, but an interesting point is raised here. Viscosity Index is the resistance of a fluid to changes in viscosity with heat. The higher the number, the less change in viscosity occurs with temperature. This is important to a suspension fluid because they start out cold and heat up with use. If the oil thins as it heats, the damping fades. Good forks are designed to compensate for this by operating more on fluid pressure than on the flow of fluid through orifices.

Even so, look at the VI numbers of some of the fluids you named. Frankly, 96 for fluid 01 is not very good, and I'm not surprised, really. Being an long time transmission technician, I'm also not really surprised at how high the VI of Dexron III is, either.

But take a look at this:

Maxima Light Shock Oil

Viscosity cSt @ 40°C 13.9

Viscosity cSt @ 100°C 5.2

Viscosity Index 359

SAE Viscosity 3wt

The viscosity index is pretty impressive by comparison. I use this fluid in all the '06+ forks I put together. It works really well.

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Thanks for everyone’s input,

does anyone have an opinion on the possible incompatible problems with the Mobil one and Teflon

Greyracer, do you have an opinion on the different characteristics between the 3wt maxima shock oil and the 5wt fork oil, does the lighter weight oil in the forks create any problems for us folks that are heavier (190lbs blowing through the valving and bottoming) I appreciate your wisdom and experience

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Thanks for everyone’s input,

does anyone have an opinion on the possible incompatible problems with the Mobil 1 and the Teflon coating

Greyracer, do you have an opinion on the different characteristics between the 3wt maxima shock oil and the 5wt fork oil, does the lighter weight oil in the forks create any problems for us folks that are heavier (190lbs blowing through the valving and bottoming) I appreciate your wisdom and experience

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Because the forks are designed around pressure balances across the valving, the weight of the oil doesn't matter as much as you might think. Some suspension whizzes believe that lighter fluids perform better once the fork is set right because they increase the sensitivity of the unit to changes in conditions. I don't think there's a real advantage to heavier oils for heavier people, but I don't know everything there is to know about it, either.

As to the Teflon question, Dexron III fluids are compatible with a very wide range of compounds that are found in automatic and manual transmissions, including Teflon itself, but it's possible that it could attack the bonding process that holds the Teflon in place in that fork, since it wasn't intended to be used in it. I've used it in '03 and '04 forks without any issues.

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That is very interesting Info. on the viscosity ratings of the different suspension fluids. Why does Enzo only recommend KYB fluids in their forks and shocks? I know that they don`t care for the S1 fork oil but they still recommend the 01 fluid. What is the advantage of running gas shock oil in the forks?

I would like to soak some used fork bushings in the Mobil 1 oil for a week or so to see if any thing happens to them.

I think that I will try some Maxima fluids in my next suspension service.

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The '06 fork calls for Yamaha Suspension Fluid S1, which is a bizarre fluid, if you've ever actually seen it. Most of the suspension guys I've talked to don't like the KYB fluids much, and they're very pricey, anyway.

Hydraulic suspension fluids don't always equate well to SAE viscosities, and in fact, they don't always even put it on the label, but an interesting point is raised here. Viscosity Index is the resistance of a fluid to changes in viscosity with heat. The higher the number, the less change in viscosity occurs with temperature. This is important to a suspension fluid because they start out cold and heat up with use. If the oil thins as it heats, the damping fades. Good forks are designed to compensate for this by operating more on fluid pressure than on the flow of fluid through orifices.

Even so, look at the VI numbers of some of the fluids you named. Frankly, 96 for fluid 01 is not very good, and I'm not surprised, really. Being an long time transmission technician, I'm also not really surprised at how high the VI of Dexron III is, either.

But take a look at this:

Maxima Light Shock Oil

Viscosity cSt @ 40°C 13.9

Viscosity cSt @ 100°C 5.2

Viscosity Index 359

SAE Viscosity 3wt

The viscosity index is pretty impressive by comparison. I use this fluid in all the '06+ forks I put together. It works really well.

You use shock oil in the forks?

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Some reason I shouldn't? Yamaha S1 is a "shock oil", and that's what is called for. When I did my first set of '06 seals, no one seemed to know w hat to use, other than S1 @ $27/qt. I started asking suspension guys, and they said that in their estimation S1 was roughly 3-4wt fluid, so I ended up with Maxima Light. Works very well.

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Some reason I shouldn't? Yamaha S1 is a "shock oil", and that's what is called for. When I did my first set of '06 seals, no one seemed to know w hat to use, other than S1 @ $27/qt. I started asking suspension guys, and they said that in their estimation S1 was roughly 3-4wt fluid, so I ended up with Maxima Light. Works very well.

I think he's confused by the "wording". Correct me if i'm wrong but fork oil and shock oil are totally different things. They would have to be because of the extreme high temperatures of the rear shock? Although forks heat up, they do not nearly to the extent of the shock. This is why Enzo recommends the K2C shock oil for the shock and the 01 for the forks?

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Shock oils do need to be more able to tolerate heat, but I see nothing in that that would preclude their use in forks.

Notice the viscosity numbers (not the claimed SAE numbers, the cSt @ temp numbers), and you can see that the Maxima Light shock is closer to the same weight as KYB 01 both at high and low temps than the others listed.

Maxima's 85/150 fork oil (5wt) was formulated as a functional duplicate to KYB 01, and comes up this way:

Grade 85/150

Viscosity cSt @ 40°C 16.2

Viscosity cSt @ 100°C 4.41

Viscosity Index 202

SAE Viscosity 5wt

...also very close, viscosity-wise. There may be a valid argument that fork fluids are better formulated to resist foaming because they run in the presence of air at least some of the time, but that's not a big concern in the '06 fork, since the cartridge is air free and closed, and the outer chamber oil does no damping. It may also be that fork oil comes with a higher content of friction reducers because they are loaded laterally.

But remember that in the beginning, I was looking for a fluid as nearly like S1 as I could find, and this is where the search lead. Yamaha had used 01 in their forks for years. I thought that they must have changed it for a reason.

I might use something different next time, though. The more I discuss this with reputable suspension builders, the more the consensus seems to be that the choice of fluid isn't quite as critical as one might think, as long as what you use is something suited to the job, and works for you.

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I think he's confused by the "wording". Correct me if i'm wrong but fork oil and shock oil are totally different things. They would have to be because of the extreme high temperatures of the rear shock? Although forks heat up, they do not nearly to the extent of the shock. This is why Enzo recommends the K2C shock oil for the shock and the 01 for the forks?

yeh that and the fact that maxima seems to differentiate shock oil from fork oil themselves. I can see using what ever you want, but I have to wonder why do they even bother making both if all that differs is the viscosity index.

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