Winter oil

[kratty]

Sorry in advance for yet another oil thread, but, I have not seen this topic addressed specifically, only in passing.

So, ONLY for those of you who switch oil viscosity during cold-weather months, what do you use?

I've seen mention of 5w40 and 0w40. Which one? And what brand?

I normally run Amsoil 5w50 and noticed that their 5w40s are Euro spec. Not sure if that really matters, but am interested in what others have to say.

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[JAJ]

5w50 will be fine through the winter, even in Cleveland. However, if you want to consider a lower viscosity, then start with a 0w because the number to the left of the "w" is the cold start viscosity. The number to the right of the "w" is the hot viscosity. So, it should be a 0w-something oil for really cold climates.

There's a third viscosity - HTHS - high temperature high shear - viscosity. It needs to be 3.7 or higher. Most "Euro" oils meet this spec, as do most heavy duty engine oils for diesels.

So, the starting point is a 0w-something with an HTHS of 3.7 or greater. Now, there are a bunch of theories on which hot viscosity you need. My theory is that the higher you rev the engine, the higher the (hot) viscosity that you'll need. So, if you set the shift lights to 6500RPM, there's no problem loading in a 0w40. There might even be a 0w30, that would work, but you might have to live with an HTHS of 3.5.

So, a "Euro" 0w40 like Mobil 1 is a candidate.

That's my theory. I live in a part of the world where I don't need to worry about it because it doesn't get that cold. Lots of other people will lots of other theories, so take your pick!

 

[MAV]

Don't just pay attention to the number on the left. The viscosity of any oil isn't measured by the "W" numbers. The true measure of viscosity is the cSt (centistokes) at a given temperature, and it is the number you need to use when comparing the viscosity of different oils. And it's most definitely NOT true that viscosity goes up at temperature goes up. It's just the opposite.

Motorcraft 5W-50 has a 40*C cSt number of 136, and a 100* number of 21. (* = degrees)

For comparison, Mobil 1 FS 0W-40 (the oil I run year round) has a 40*C cSt number of 70.8 and 100* of 12.9. That tells me that at 40* C, Mobil 1 0W-40 is nearly half the thickness of Motorcraft 5W-50. This is for new oils. After a few thousand miles of use, all oils will shear to a lower cSt as the viscosity modifiers are used up. Knowing what we know through multiple reports of used oil analysis of Motorcraft 5W-50, it quickly shears down to a 40 (or less) after a couple thousand miles.

I'm not suggesting that you not use MC 5W-50. I am suggesting that you look up the PDS (product data sheet) for any particular oil you're considering to make a valid comparison.

References:

Motorcraft 5W-50 PDS

Mobil 1 FS 0W-40 PDS

 

[JAJ]

... And it's most definitely NOT true that viscosity goes up at temperature goes up. It's just the opposite...

Thanks for pointing out that my wording was ambiguous. I've edited the sentence to hopefully make it clearer.

What I was trying to communicate is to pick a higher viscosity oil (bigger right hand number) when running higher RPMs. Or, put another way, if you lower your max RPM you can consider using a lower viscosity oil.

 

[Hack]

Thanks for pointing out that my wording was ambiguous. I've edited the sentence to hopefully make it clearer.

What I was trying to communicate is to pick a higher viscosity oil (bigger right hand number) when running higher RPMs. Or, put another way, if you lower your max RPM you can consider using a lower viscosity oil.

I think you're confusing viscosity and film strength.

 

[JAJ]

I think you're confusing viscosity and film strength.

Nope. Film strength is a function of chemistry, not viscosity.

I was keying off of Ford's explanation for why they went to 5w50 for the Roadrunner. The interview indicated that they went to a full syn 5w50 because of the foaming that happens at high rpms when the crank whips the oil. The Coyote, substantially the same engine with a lower max RPM, was spec'd 5w20.

So, there's no more science to it than that. We don't know what happens inside a Voodoo at low RPM, but it's probably pretty tame compared to 8250. So, keep the revs down and if you're ever going to be fine with a lower vis oil, that's when it will be.

 

[Demonic]

I would not want to be in a situation where the engine fails within warranty and the analysis showed I was using a different oil than specified.

 

[kratty]

I would not want to be in a situation where the engine fails within warranty and the analysis showed I was using a different oil than specified.

My goals are as follows:

Find an oil to--
1) Protect the engine
2) Actually reach 180 during cold-weather driving
3) See #1

Does it exist?

 

[JAJ]

Best option to protect the engine and your warranty is to stay with Motorcraft 5w50.

 

[DocWalt]

My goals are as follows:

Find an oil to--
1) Protect the engine
2) Actually reach 180 during cold-weather driving
3) See #1

Does it exist?

Stick some tape over the oil cooler grille or ziptie a piece of cardboard on. Looks like crap but it warms the oil up properly then

 

[mustang1]

Mustang needs an active grille. Get the engine oil to 180F faster in cold weather.

 

[bellwilliam]

Motorcraft 5W-50 has a 40*C cSt number of 136, and a 100* number of 21. (* = degrees)

For comparison, Mobil 1 FS 0W-40 (the oil I run year round) has a 40*C cSt number of 70.8 and 100* of 12.9. That tells me that at 40* C, Mobil 1 0W-40 is nearly half the thickness of Motorcraft 5W-50. This is for new oils. After a few thousand miles of use, all oils will shear to a lower cSt as the viscosity modifiers are used up. Knowing what we know through multiple reports of used oil analysis of Motorcraft 5W-50, it quickly shears down to a 40 (or less) after a couple thousand miles.

doesn't that mean Mobil 1 FS 0w-40 will only have 1/2 the viscosity of Motorcraft 5w-50 when I rev the engine to 8,250rpm on track ? how is that better ?

 

[MAV]

I wouldn't use 0W-40 on the track.

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