Yamalube 01 / S1

After making some calls here is what I was told by a reliable suspension guy.

01 is made for open cartridge forks. When pored out it would look like a 10wt. It was designed to operate under cavitation and foaming. It can be used in the newer forks but would be really stiff.

S1 is a 5wt and designed to work in the twin chamber system.

There was a little bit more to it, and something about the air in the old forks.

There's a lot more to this, apparently. I've been snooping in the suspension forum. The posts by DaveJ should be given a good deal of credence:



I also have a couple of questions out, but from past experience and info, "01" is a 5wt, and S1 is somewhat lighter, at least in appearance. That's not the same as actually measuring the viscosity, however, so we can't make book on it at this point. But the above is interesting reading.

I can say for certain, though that at least 4 people that I know including myself like the fork with Maxima Light Shock Fluid (3wt) in it.

He did say that the 01 because of the heat and foaming acts like a 5wt but when cold looks like a 10wt, hence the stiffness is the twin chamber forks.

I don't know about that. Could be partly right, but seeing the stuff in person would give you a different perspective. The after market fluids are formulated somewhat differently, have different additives, and probably higher viscosity indexes. From the first link:

...However, that doesn't answer the question on why Yamaha switched fluids and why they recommend that S1 be used for the 05-06 bikes.

So I called my contact at Yamaha and he said that the S1 was developed for the new 05 fork as a fork fluid that could meet new anti-foaming demands. In other words, the S1 has an anti-foaming agent added to it that the older 01 does not have. ...

It's also been noted that Yamaha suspension fluids are hygroscopic (they have an affinity for and absorb water). This leads to the observation many have had that the fluid appears gelatinous, or almost mucus-like when it has some time on it, even though it still feels thin between the fingers.

I'm waiting to hear if I get any answers back before I speculate further.


How does the Bel Ray 5wt fork oil pan out in the advanced suspension? My 02 426 is hardly cutting edge but it handles beautifully with .48 kg/m fork springs, a 5.8kg/m shock spring, using Yamaha Yamalube 01 fluid in the forks. I am considering using the Bel Ray 5 wt since I had good fortune using it in the past in other bikes and conventional forks. Would the Bel Ray fork oil p[erform as well as the 01 or would it be lacking?

I couldn't find the viscosity index information at Bel Ray's site, may not be looking in the right place. Also, does the Bel Ray match up in the longevity department?

I have used the Yamalube 01 since the first oil change out in October 2002. I change oil on about a 6 month interval, more often if it is a wet or humid period. I have not seen the gelatinous appearance but I am extremely leery of hygroscopic contamination since our cranes' and lift trucks' hydraulics are a worry point for our family's construction company in safety and maintenance.

As far as seal life I actually still have the original seals with no leaks as of yet. I do clean under the seals and the wiper regularly and keep the grunge off of the fork's lower legs.

My apologies for hijacking the thread but the original question was well stated and the information you gave from the links and you input helped me immensely. I went to our regular shop but other than the Maxima 5wt and other Maxima fork oils they don't carry any fork oil. Their knowledge is basic and is sound but beyond viscosity index they are beyond their knowledge. Thanks for the time and the input. I am headed into the suspension forums to research a bit.


Any good 5wt fork oil should be fine in the single chamber KYB's, including Bel-Ray.

On the original question, I got this from MX-Tech:

I asked, "What is the SAE equivalent of Yamaha's "S1" fork/shock fluid used in the '06 YZ450? I've used 3wt a couple of times, and it seems fine, but no one seems to know the definitive answer to this.

One person now says it's a 5wt, which I had thought was equivalent to the "01" fluid."

Their response:

"Your best bet for replacement KYB fluid is enzo. We use motorex 2.5wt, but its more like the industry standard 5 wt. I personally dont like like the stock KYB fluid. All top shelf 5wts are good alternatives.

I have a good friend who is a chemical engineer for Pennzoil, maybe I should run this by him."

Not directly on point, I suppose, but still interesting.


Thanks for the quick reply, I now feel better about using Bel Ray 5wt fork oil in my 02. It is getting hard to get Yamalube 01 here other than an on line order. The Yamaha dealer dose not like to order the cans for some reason. I called yesterday and the parts guy acted like it wasn't even made. I went through the product description and he stuttered and said they wouldn't carry it and acted like I had asked for a free bike about ordering the oil. No real surprose but worth trying. I suppose I will drive to Mobile,AL or Orange Beach, AL for my next Yamaha, now.

BTW, after rereading my post I realized my dyslexic fingers (or my addled 50 y.o. brain) put down 4.8 kg/m whan my shocl spring is 5.9 kg/m. Just didn;t anyone to wonder why the 195 # guy was riding on mini springs.


Another response from a suspension pro:

"The answer is there is no direct correlation. SAE uses tests that are different for oils than the hydraulic industry uses.

Additionally S1 is just a brand designation not necessarily a measurement of any specific parameter or value.

I would say generally a S1 is around a 5 wt but again it’s not actually a real comparison."

One other point: The term, "Viscosity Index" has been mentioned. This is a numeric value which indicates the amount of viscosity change that occurs with temperature. A high value means that the viscosity of an oil will remain more constant as it heats or cools than an oil with a lower VI will. Higher numbers, therefore, are generally better for hydraulic fluids, because it means that the performance of the device will be closer to the same regardless of temperature.

However, it does not have anything to do with the actual viscosity of the fluid. Viscosity and Viscosity Index are two independent values.

Roger the viscosity index definition GR. My only attention to the VI number was the guy at the shop was constantly throwing the O-1 VI number out because the had been told what the VI for O-1 was at a class he took for Suzuki maintenance last week. And that exhausted his knowledge of oil viscosity and VI knowledge.


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