Ford: High altitude requires 0W oil. Why?

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In the 2022 F-150 and Expedition owner's manuals Ford states: "If you use your vehicle regularly above the altitude of 7500 ft (2,286 m) and under the temperature of -4.0°F (-20°C), it is recommended to use the alternative engine oil", where the "alternative engine oil" is 0W-30 instead of the normal 5W-30. Why do you think altitude makes a difference?

Here is an excerpt from the manual:

Materials
NameSpecification
Engine Oil - SAE 5W-30 - Synthetic BlendWSS-M2C961-A1
Alternative Engine Oil for Extremely Cold Climates
To improve engine cold start performance, use the following engine oil in climates where the ambient temperature reaches -22.0°F (-30°C) or below.
Materials
NameSpecification
Engine Oil - SAE 0W-30 - Synthetic BlendWSS-M2C963-A1
Cold Climate Oil Viscosity Chart 5W30  0W30

Note: If you use your vehicle regularly above the altitude of 7500 ft (2,286 m) and under the temperature of -4.0°F (-20°C), it is recommended to use the alternative engine oil.
 
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Altitude and temperature are most certainly connected. Those mountains on the equator get snow don’t they?
Ok good point, I had to google. So the snow line is at like 14,000 feet... I know what you're saying, it just seems redundant to include altitude. Maybe this is their way of dealing with really dumb customers. "You go high, you get cold..."
 
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Ok good point, I had to google. So the snow line is at like 14,000 feet... I know what you're saying, it just seems redundant to include altitude. Maybe this is their way of dealing with really dumb customers. "You go high, you get cold..."
Because you have to draw everything to people.
What is the targeted audience? US customers. That attitude, where roads are in the US, means cold winters.
 
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Altitude and temperature are most certainly connected. Those mountains on the equator get snow don’t they?
Approximately 3.5*F or 2.0*C for every 1,000' of elevation, on an average location and day.
However, there's no need to include altitude because it's only a correlating factor. It's temperature that matters.

Can anyone think of a reason altitude / air density matters in and of itself, not through its correlation to temperature? I doubt it because piston airplane engines don't have special oil requirements for altitude. They do have fuel requirements (low vapor pressure) but not for oil.
 

Alien

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Note that Ford has no recommendation or requirement for the owner to use 0W between the temperatures of -4F and -22F if they stay below 7500 feet. Below -22F they are required to use 0W. A couple of observations:

1) They still want the owners to use 5W if at all possible (meaning temperatures above -22F). Otherwise, why not just specify 0W30 for all temperatures as some other OEMs do. That tells me they have reason to believe that 5W oils are better than 0W oils at most temperatures and altitudes.

2) They have reason to believe that above 7500 feet, 0W is better than 5W at temperatures below -4F. But what is the reason?

Some history: Before 2017, 5W30 was the only oil they allowed to be used, regardless of temperature and altitude, per their user's manual. In 2017, they recommended but did not require 0W30 meeting a new Ford spec for temperatures below -22F. No oil available in the US claimed to meet that new spec. In 2021, M1 0W30 AFE finally claimed to meet the Ford spec (on their bottles, but still not on their webpage), and Ford changed their recommendation into a requirement and added this new recommendation tied to altitude.

Any theories on what Ford's thinking is, and why it is tied to altitude? The theories proposed so far have certainly been creative, but if Ford is simply trying to say use 0W in cold weather, it would have been more effective to tie the recommendation to latitude rather than altitude.
 
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Any theories on what Ford's thinking is, and why it is tied to altitude? The theories proposed so far have certainly been creative, but if Ford is simply trying to say use 0W in cold weather, it would have been more effective to tie the recommendation to latitude rather than altitude.


It gets colder the higher you go. It’s that way no matter where you are on the planet. Hawaii’s tallest mountain has snow on top.
 

Alien

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Approximately 3.5*F or 2.0*C for every 1,000' of elevation, on an average location and day.
However, there's no need to include altitude because it's only a correlating factor. It's temperature that matters.

Can anyone think of a reason altitude / air density matters in and of itself, not through its correlation to temperature? I doubt it because piston airplane engines don't have special oil requirements for altitude. They do have fuel requirements (low vapor pressure) but not for oil.
It could be startup related. With an airplane, the engine is started at a lower altitude and is only elevated to a high altitude once the engine is already warmed up.
 

Alien

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It gets colder the higher you go. It’s that way no matter where you are on the planet. Hawaii’s tallest mountain has snow on top.
Right. But a lot more people live in a cold latitude than a high (above 7500') altitude.
 

Alien

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You may be able to tell from my icon that I am familiar with high mountains and the effect elevation has on temperatures ... :)
 

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Could it have anything to do with the operation of bypass or relief valves at startup at high altitude? They are pressure related and may operate differently at lower air pressure.
 
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Oil bypass & relief valves are based on oil pressure, not ambient air pressure. For example the oil filter bypass activates based on the oil pressure difference across the filter.

I gather from this thread that air pressure or altitude has no direct impact on oil selection. It is temperature that matters, and altitude is only loosely correlated with that. At least, nobody's come with anything that seems plausible.
 
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Note: is this a direct quote from the manual (emphasis mine)?
If you use your vehicle regularly above the altitude of 7500 ft (2,286 m) and under the temperature of -4.0°F (-20°C), it is recommended to use the alternative engine oil.

If so, it is logically incorrect. Clearly, if you're at sea level and it's below -4* F, then the thinner oil is appropriate no matter what your altitude is. The manual should say or, not and. Or just not mention altitude at all.
 
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