# Any truth to this viscosity explanation....?

...or is this just another idiotic statement? From a Saturn board: "EXAMPLE 10w-30 10=The pumping equivalent of the oil at 32 degrees F. (0c) in comparision to water (water being of "0" Weight) 30=The pumping equivalent of the oil at 212 degrees F. (100c) in comparison to water (water being "0" weight) Keeping this in mind a "0" weight oil would pump as readily as water, a "30" weight oil would pump as readily as 30 times the "thickness" (or viscosity) of water." Is water '0' weight, if one is using SAE viscosity calculations?

#### Quattro Pete

That is wrong, at least regarding the first of the two numbers (before w). At 0C, water turns into ice, so it's hard to talk about its pumpability. And at 100C, water is boiling, so again, not sure if it's even possible to measure its pumpability. AFAIK, the first numer (before w) is estimated at some temperature that is quite a bit below 0C, and again, at such temperature comparing it to water doesn't make any sense, because water becomes a solid at that point.

#### XS650

A person could make a more incorrect statement, but would have to work at it. He is so wrong there is nothing there to correct.

#### bepperb

It's an idiotic statement. The "winter weight" has nothing to do with 32 degrees. Water isn't 0 viscosity.

#### Propflux01

So What IS the viscosity of water? And at what temps (other than frozen or boiling)?

#### TallPaul

Isn't the viscosity of water 1 cSt at 100C? I really don't know but think I saw something like that in a list comparing viscosities of many different substances including blood, honey, etc.

#### bepperb

I'm pretty sure water is a gas at 100c...

#### Quattro Pete

Originally Posted By: TallPaul
Isn't the viscosity of water 1 cSt at 100C? I really don't know but think I saw something like that in a list comparing viscosities of many different substances including blood, honey, etc.
It's 1 centipoise at room temperature... http://hypertextbook.com/physics/matter/viscosity/

#### oilyriser

Water has a very high viscosity index.

#### TallPaul

Duh, right. 100C is defined as the boiling point of water, presumably at sea level, so the 1 cSt must have been room temp which would be more relevant for a list of diverse substances found around the house.

#### ekpolk

Originally Posted By: oilyriser
Water has a very high viscosity index.
That's true, but alas, it has very poor pumpability during the winter months up in your neck of the woods. . . As for the OP's question, that statement is a mess. You mind telling us where it came from?

#### ekpolk

Another thought: this sort of confusion is exactly why the SAE grade system just needs to go. In my opinion, oils should be labeled with hot vis, cold vis, and minimum temp at which the oil may be used. We can debate the units to be used, how it should be presented, and so forth, but stating the absolute numbers would eliminate much mystery, confusion, and bufoonery on questions like this.

#### d00df00d

Wow. Talking about engine oil viscosity in reference to temperatures at which water is not a liquid... Truth be told, I can't help but feel like this person put in a good effort. Invite him or her over to BITOG!

#### oilyriser

You can add antifreeze, and it flows down to -40, but that reduces the VI. Methanol doesn't affect VI as much, but it's too volatile.

#### CATERHAM

Originally Posted By: ekpolk
Another thought: this sort of confusion is exactly why the SAE grade system just needs to go. In my opinion, oils should be labeled with hot vis, cold vis, and minimum temp at which the oil may be used. We can debate the units to be used, how it should be presented, and so forth, but stating the absolute numbers would eliminate much mystery, confusion, and bufoonery on questions like this.
Agree, and it's been discussed before on this forum from time to time. Perhaps a BITOG proposal should be made to the SAE? For eg., a 10W-30 dino using actual kinematic vis could be labeled 750W-10. A 5W-30 dino would be typically 550W-10. PP 0W-20 would be labeled 300W-8.4. You could add an optional third prefix number representing temps much colder than 0C, say at -40C. What a revelation, using real viscosity figures!

#### TallPaul

Originally Posted By: oilyriser
Water has a very high viscosity index.
Here we go, the Kinematic viscosity of water (cSt)ranges from 1.9 at 32F to 0.3 at 212F. Table of viscosity of water.

#### mechtech2

I knew the density of water changed with temperature, but I had no idea the viscosity ranged so much for plain H2O.

#### tom slick

Originally Posted By: bepperb
I'm pretty sure water is a gas at 100c...
It can be either liquid or gas at 100c because it is absorbing energy to make a phase change. At 101c it does have to be gas under normal atmospheric pressure. Same at 0c, solid or liquid, giving off energy to phase change. at -1c it has to be solid.

#### SpitfireS

Originally Posted By: ekpolk
In my opinion, oils should be labeled with hot vis, cold vis, and minimum temp at which the oil may be used.
What about car manuals? How would/should they tell you what oil to use? 550W-750W / 9.6-12.5 ? And why would the not recommend 400W? The lower the better right? The oil bottle should have a sort of shear stability or HTHS on it too I suppose or is SM / ACEA A5 enough for that?

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