U&A
Senior Member
- Joined
- Apr 29, 2016
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- Michigan
- Ram Year
- 2016 3500 SRW
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- 6.4 HEMI
Density plays a role in the viscosity of an oil at a given temperature outside of any modifiers like VII's, which increase viscosity on other principles than just fluid density as they are actually less dense when they expand. However the density change is not a 1:1 viscosity change as noted by the 2nd link's set of charts. A prime example of this is the chart for the straight 30 weight. Pretty much the only numbers you should be concerned with are the viscosity at a given temperature as the density will also either change differently or have a different impact depending on the nature of the base oil and any modifiers like VII's.
https://www.engineeringtoolbox.com/...cant-volume-correction-ASTM-D1250-d_1943.html
https://wiki.anton-paar.com/en/engine-oil/
If im understand the charts correctly. SAE30 (Straight weight) has slightly more density than their 2nd place contender 15w40.
Kinda figured that
This is exactly what most of us have been assuming all along is the closer together the numbers are to a straight weight the denser oil (relative to its counterpart in a multi viscosity)
The one thing most people don’t know is straight weight still act like multi weight oils.
For example. A lot of SAE30’s could almost pass as a 10w30. This makes me even more want to try 10W-40 again. Or even something more off the wall.
Im going to contact dave if nobody else hasn’t already and see if I can get density numbers on their blue label oil’s.
[emoji3595]Burla, did you do this already?
Iv often wondered if conventional oils are slightly more dense than full synthetics when they are of similar viscosity.
For example True synthetic oil molecules are extremely symmetrical like a sphere. Whereas conventional oil molecules are blockier. Though the sphere shaped molecules will provide better protection the blockier ones almost have more resistance to being pushed out of the way.... so that could make them more “dense” ....? Think of one of them ball pits that kids play in. The sphere’s move easy. Now make the same pit with plastic blocks of different size and shape. They Don’t move so easy now...
Density is definitely something to keep looking into IMO...
Sent while firmly grasping my redline lubed RAM [emoji231]