SAE Paper on Engine Wear with 20 wt. oil

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What do you find hard to believe? What other benefit is there? It is for load modulation.
Yes, to save fuel. So why not run lower volume all the time, or at least more of the time, and save fuel across more of the Cafe test?

So obviously flow plays in here at some point. How that is affected by viscosity of the chosen oil is a pure guess unless you have access to the Toyota test data.
 
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You can only run a minimum volume based on the design and condition of the engine. Oil pumps are typically oversized to account for the worst possible requirement for the engine.

As long as the pump is pumping then the oil will flow. Flow does not lubricate, film thickness does in that it keeps parts separated. The only time flow really matters is when it is flowing to the pump pickup tube. If the oil is too cold it will gel in the vicinity of the pickup screen under shear and then the pump will cavitate. But with a proper selection of a winter rating then the oil will flow to the pump and will then flow in the engine.

Variable displacement oil pumps save energy by reducing the load on the engine rather than having a constant load.
 
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All engines can run on multiple viscosity grades with HT/HS ranges from 2.3 and > with little issue. It's not an absolute. Never has been. Only a very select few engines need an exact viscosity. But even then, there is also variation within a grade from low to high.
Not all. Maybe engines designed for 0W-16.
From a paper I have, the study concluded that going below 2.6 HTHS is where increased wear begins. If I remember correctly the sweet spot was 3.1 or 3.2.
 
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All engines can run on multiple viscosity grades with HT/HS ranges from 2.3 and > with little issue. It's not an absolute. Never has been. Only a very select few engines need an exact viscosity. But even then, there is also variation within a grade from low to high.
Need how? As in a minimum MOFT? All engines need that but there are no automobile engines that “need” an exact viscosity. For one thing an oil is only at an “exact” viscosity at a stable operating temperature. If they needed an exact viscosity to prevent damage then we’d have a boatload of failures here in the upper Midwest.
 
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Just for curiosity:

My Ram's 5.7L HEMI has oil temps in the 222-227F range under normal driving. At that temperature, is a XW-20 still a 20-wt? Or has it become a 16wt?
 
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Need how? As in a minimum MOFT? All engines need that but there are no automobile engines that “need” an exact viscosity. For one thing an oil is only at an “exact” viscosity at a stable operating temperature. If they needed an exact viscosity to prevent damage then we’d have a boatload of failures here in the upper Midwest.
I agree. What I was thinking were the very select few engines that "supposedly" were designed around a 20 grade to function properly. I have no proof this is the case. I personally think you can run any engine on a variety of different viscosities with no issues.
 
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So the thinner oil provided better flow? Or provided better lubrication as the engine was warming up? Did they provide any explanation. Just curios.

FWIW I had a 4.6. It was find up to 180K when I sold it except for 1 burnt valve at around 80K. Just one - the rest were fine. Had the one valve seat replaced and valves ground ant it was fine the rest of the way.
That’s been a long time ago so I really don’t remember. FWIW our fleet got low bid 15W40. Only lost one 4.6 due to camshaft galling in head. The best I recall was this actually happened while a Tech had the car idling in his bay. Ford did help us with the repair but rained down on us about using 5W20.
 
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What is your opinion on the 20 weight oils at the time of the aforementioned article as compared to 20 weight oils produced today? Just curious.
The thickness of the oil film. Extra heat or fuel dilution or permanent shear gives the advantage to a 30wt.
 
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Marginally better protection may mean the difference between a Honda V6 burning oil at 100K miles, or 300K miles. The difference in piston ring wear is 0.005 inches. Some well known examples of low tension piston rings don't seal once a nominal level of wear has taken place. The fix is simple enough, replace the rings with a "newer design" that has more tension.

I bring this up because most motorists don't know what's inside their engine or the mode of failure.
 
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Marginally better protection may mean the difference between a Honda V6 burning oil at 100K miles, or 300K miles. The difference in piston ring wear is 0.005 inches. Some well known examples of low tension piston rings don't seal once a nominal level of wear has taken place. The fix is simple enough, replace the rings with a "newer design" that has more tension.

I bring this up because most motorists don't know what's inside their engine or the mode of failure.
Did you really mean 5 thou, or 5 ten-thousandths? .005 seems like an absolute disaster of wear on rings, since that will also effectively change the endgap as well (until all tension is gone from the outside surface, of course)?
 
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Did you really mean 5 thou, or 5 ten-thousandths? .005 seems like an absolute disaster of wear on rings, since that will also effectively change the endgap as well (until all tension is gone from the outside surface, of course)?
Clearances or tolerances ?:love:
 
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