What does the first number (0w) actually mean? Most consumers in my area think that it means this oil starts out as a 0w oil and thickens up to the last number (30) as it becomes hot. Will the ow -30 oil act the same in cold and hot weather?
Explain oil numbers please?
- Thread starter yankees1
- Start date
- Status
Many have this portion of Motor Oil 101 backwards, as oil is thin at a full operating temperature of 212 degrees F, and thickens as it cools down to the xW grade rating.
No motor oil is thin at cold temps - they are all similar to thick syrup in viscosity.
In your 0w30 example, a 0W is 6200 cP @ -35C and thins to 10-12 cSt as it warms up.
No motor oil is thin at cold temps - they are all similar to thick syrup in viscosity.
In your 0w30 example, a 0W is 6200 cP @ -35C and thins to 10-12 cSt as it warms up.
I could be wrong here, but I think the original designations were intended to reflect the weight of the oil at 0C and 100C. In other words a 10w30 oil behaves and is as thick as a straight 30 wt oil at 100C (near operating temp), and it behaves like a straight 10 wt. oil at 0C or freezing. The problem is that a 10 wt oil is still very thick at 0C. A 0 Wt oils is also very thick and really to thick to be ideal. However, that is the best we have to work with these days. At some point I believe there will be a need for negative -Xw numbers, or an overhaul of the numbering system. People that think a 0w30 oil is too thin at startup are not understand this.
And while the original intent was based on this 0 and 100 C system it has now changed to a CCS and MRV spec at colder temps. And typically a multigrade is a compromise to some degree. Often it is not as thick as a 30 hot, and not as thin as a zero cold.
What is your point? I know that article well, and tried to explain it in an understandable manner. I also have an engineering text from the 60's when multigrades were starting to appear, and have quoted some information from that era when standards were being developed.
0w can pump in an engine at a VERY FREEZING ambient temp even though the oil's thick. -30 has a specific resistance to flow when it's thin, at operating temp. -20 has a little less resistance to flow and -40 has a little more.
Excellent Pabs.
That's one of the easiest to understand, yet comprehensive, descriptions of grade designations I've seen posted.
And I have to echo 427Z06's comment, nice link, a very complete explanation of the motor oil viscosity "puzzle".
Also, it's authored by Mark Sztenderowicz, of Chevron, who typically puts out some very good material on the subject of lubricants.
Also, it's authored by Mark Sztenderowicz, of Chevron, who typically puts out some very good material on the subject of lubricants.
- Status
