What;'s the "W" stand for?
What;'s the "W" stand for?
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What;'s the "W" stand for?
A couple of people I know have been debating what the "W" stands for when listed in the weight.For instance 10W30,4W20,20W50 etc....
One says winter the other says weight.
I them to see the real meaning of the "W" so I don't have to listen to them anymore
.
Thanks.
One says winter the other says weight.
I them to see the real meaning of the "W" so I don't have to listen to them anymore
.Thanks.
Elder User
Joined: Apr 2002
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From: Kentucky
What;'s the "W" stand for?
In a multi-grade oil the 'W' indicates its a 'winter' rated oil. In the case of 10W30, the base oil is a 10 weight suitable for winter use which hepls with cold starting, and the manufacturer adds poymers which thicken the oil to a 30 weight when it warms to operating temperature.
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From: VA/USA
What;'s the "W" stand for?
Though my understanding has been winter, it sounds as though it's a bit redundant - as a 10 "weight" oil would only much be any good for winter - unless you lived at one of the poles or something...right??? 
Postmaster
Joined: Aug 2001
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From: Trussville, Alabama
What;'s the "W" stand for?
Some clarification (and someone please correct me if I am wrong)
for 10W-30 as an example:
The 10W means the oil has the viscosity of a straight 10 weight oil in "winter" - which I believe is measured at 0 degrees celsius.
The 30 means the oil will thin to the EQUIVALENT of a straight 30 weight at higher temps - which I believe is measured at 100 degrees celsius.
Added polymers effectively maintain the viscosity of an oil which acts like a 10 weight when cold, so that it acts like a 30 weight when hot.
It is my understanding that the added polymers are what makes 10W-40 an oil to be avoided...the base stock is dilluted too much by the addition of enough polymers to provide the 30 weight difference between 10 and 40; too much polymer and not enough oil.
This does not apply to 20W-50. I believe because there is less polymer need due to the higher viscosity of the base (20 weight) oil.
Brian A
for 10W-30 as an example:
The 10W means the oil has the viscosity of a straight 10 weight oil in "winter" - which I believe is measured at 0 degrees celsius.
The 30 means the oil will thin to the EQUIVALENT of a straight 30 weight at higher temps - which I believe is measured at 100 degrees celsius.
Added polymers effectively maintain the viscosity of an oil which acts like a 10 weight when cold, so that it acts like a 30 weight when hot.
It is my understanding that the added polymers are what makes 10W-40 an oil to be avoided...the base stock is dilluted too much by the addition of enough polymers to provide the 30 weight difference between 10 and 40; too much polymer and not enough oil.
This does not apply to 20W-50. I believe because there is less polymer need due to the higher viscosity of the base (20 weight) oil.
Brian A
Sit. Stay.
Joined: Oct 2001
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From: Washington State
What;'s the "W" stand for?
>In the case of 10W30, the base oil is a 10 weight suitable for winter use which helps with cold starting, and the manufacturer adds poymers which thicken the oil to a 30 weight when it warms to operating temperature.
Um...common misconception.
The first number does indeed denote the weight of the base stock.
In the case of 10W-30, the oil will only thin as much as a 30 weight (the second number) would at operating temp. Percentage wise...
Um...common misconception.
The first number does indeed denote the weight of the base stock.
In the case of 10W-30, the oil will only thin as much as a 30 weight (the second number) would at operating temp. Percentage wise...
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From: Kentucky
What;'s the "W" stand for?
Monsta, you're saying the polymers don't actually thicken the oil, they keep it from thinning out more than 30 weight when hot? It's late, so my brain is trying to keep up but I think I get it. 
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Sit. Stay.
Joined: Oct 2001
Posts: 18,308
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From: Washington State
What;'s the "W" stand for?
You got it almost.
They keep it from thinning as much as a 30 weight would at operating temp.
Here...let's make it easy.
Say 30W oil at 250° thins 25%. (Just an example folks...)
On a multi-V oil, the base stock (10W in "our" example) would only thin 25%.
They keep it from thinning as much as a 30 weight would at operating temp.
Here...let's make it easy.
Say 30W oil at 250° thins 25%. (Just an example folks...)
On a multi-V oil, the base stock (10W in "our" example) would only thin 25%.
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