What does 10w30 mean on oil cans? Is it 10 winter and 30 what? And how is it determined?

On Sat, 17 Feb 2018 11:53:34 -0800 (PST), wrote:

What does 10w30 mean on oil cans? Is it 10 winter and 30 what? And how is it determined?

Viscosity? 10 Weight in Winter, 30 Weight in Summer?

On 2/17/2018 2:53 PM, wrote:
What does 10w30 mean on oil cans? Is it 10 winter and 30 what? And how is it determined?

Was going to type this but easier to clip from google hit:

The first number '10W' is the viscosity of the oil at cold temperature
and the second number is the viscosity at 100 °C (212 °F). The two
numbers used are individually defined by SAE J300 for single-grade oils.

As this chemist understands it, there are polymers in the oil that
lengthen with temperature causing the viscosity increase.

On Sat, 17 Feb 2018 15:09:03 -0500, Frank "frank wrote:

On 2/17/2018 2:53 PM, wrote:
What does 10w30 mean on oil cans? Is it 10 winter and 30 what? And how is it determined?

Was going to type this but easier to clip from google hit:

The first number '10W' is the viscosity of the oil at cold temperature
and the second number is the viscosity at 100 °C (212 °F). The two
numbers used are individually defined by SAE J300 for single-grade oils.

As this chemist understands it, there are polymers in the oil that
lengthen with temperature causing the viscosity increase.

I always found in interesting how viscosity changes in oil labeled as
such. What happens to 40W or 90W gear oil? Gear boxes and vehicle
differentials go from cold to hot pretty quick...

On Sat, 17 Feb 2018 11:53:34 -0800 (PST), wrote
in

What does 10w30 mean on oil cans? Is it 10 winter and 30 what? And how is it determined?

The viscosity of the oil at operating temps is 10, but it's
lubricating effectiveness is 30.
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On 2/17/2018 3:30 PM, Oren wrote:
On Sat, 17 Feb 2018 15:09:03 -0500, Frank "frank wrote:

On 2/17/2018 2:53 PM, wrote:
What does 10w30 mean on oil cans? Is it 10 winter and 30 what? And how is it determined?

Was going to type this but easier to clip from google hit:

The first number '10W' is the viscosity of the oil at cold temperature
and the second number is the viscosity at 100 °C (212 °F). The two
numbers used are individually defined by SAE J300 for single-grade oils.

As this chemist understands it, there are polymers in the oil that
lengthen with temperature causing the viscosity increase.

I always found in interesting how viscosity changes in oil labeled as
such. What happens to 40W or 90W gear oil? Gear boxes and vehicle
differentials go from cold to hot pretty quick...

Liquids normally get less viscous when heated. For gear oil I don't
know if that is room temperature viscosity or operating viscosity and
without additives they should thin with temperature.

Also do not know what these number are in real units of centipoise where
water is about 1 at room temperature.

Years ago I used to deal with viscosities of polymers when I worked on
them. Some thicken and some thin with shear. Homeowner has seen this
with latex paint which flows easily when brushed but does not drip as
readily as oil based paints.

On Sat, 17 Feb 2018 11:53:34 -0800 (PST), wrote:

What does 10w30 mean on oil cans? Is it 10 winter and 30 what? And how is it determined?


I'll try to make it simple and answer the questions raised in some of
the replies.

First of all,ALL oil gets thinner when it is heated up, so no, it is
not 10 weight when cold and 30 weight when hot.

Close though.

The first number (10w) means it "behaves like a 10 weight oil at low
temperatures" when it is cold, and the 30 means it "behaves like 30
weight oil at high temperatures" when at high temperatures.

Hot 10W30 oil is still thinner than cold straight grade 10

The temperatures and test schedules are specified in SAE papers

Compared to a 10 weight straight grade oil, 10W30 does not thin out as
much when hot.
Compared to a 30 weight straight grade oil, it does not thicken as
much when cold.

In a standard (non synthetic) oil this is accomplished by adding a
significant amount of "long chain polymer" viscosity index improvers
that coil up and uncoil under influence of temperature change to
thicken the oil when hot, so when those molecules "shear" ofer time,
the oil loses hot viscosity.
This is one reason oil needs to be changed, even if it is still
"clean"

Synthetic oils, by their very nature, have a better "viscosity index"
so synthetic oils use much less, and different, viscosity index
improvers, and their viscosity does not change nearly as much over
time/usage as conventional multi-grade oils - and therefore can last
longer between changes.

Gear oils are also available in "straight grade" and "multigrade" -
ie SAE 90 and SAE 75W90