Oil viscosity numbers, and does "Winter" actually matter?

ZeeOSix

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Many auto manufacturers are embracing a 0wX for their suggested oils, including 0w40 for performance oriented vehicles. They are not doing it for winter performance and super cold starts.
They are mainly doing it for CAFE targets. Thinner cold oil (W rating) saves a sliver of fuel on every cold start. The other benifit is they never have to worry about cold start-up pumpability for cars used during very cold winters.
 

OVERKILL

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They are mainly doing it for CAFE targets. Thinner cold oil (W rating) saves a sliver of fuel on every cold start. The other benifit is they never have to worry about super cold start-up pumpability for cars used during very cold winters.
Yes, there's that "universal" aspect, which is why 0w-40 was so popular.
 
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For most parts and in general (average/typical driver), if the engine has oil, it will survive ... Also in general going one viscosity grade higher than recommended is much safer than going lower. Not saying it's going to blow up your engine but I would be more careful doing this:

"I use 0w20 in my 3.5 Ecoboost. Yes you heard that right. It's not a typo. I use 0w20 in my 3.5 Ecoboost engine, which normally is supposed to run 5w30 according to Ford."
 
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Regarding 10W-30s:

I can neither confirm nor deny that I have dated chubby girls with low self esteem. :unsure::ROFLMAO:
 

ZeeOSix

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I use 0w20 in my 3.5 Ecoboost. Yes you heard that right. It's not a typo. I use 0w20 in my 3.5 Ecoboost engine, which normally is supposed to run 5w30 according to Ford. I switched from using 5w20, 5w30 and 10w30 to 0w20. I've been using 0w20 for almost 20k miles now, because I do believe that 0w oils are objectively better in cold starts (in all ambient temps). I believe that there is no need to use anything with a thicker W rating, because of the objective reasoning I stared above.
Go blast it around a track for while with that 0W-20 to get the oil temperature to 250+ F for an extended time and let us know how it goes. Any car driven mellow 99%+ of the time on the street will not "blow-up" going down an oil grade. But how do you know you are not causing more wear by using a thinner oil. Technical studies certainly do show that thinner oil can cause more wear on certain engine components. Thinner oil viscosity reduces the minimum oil film thickness between moving parts, and the smaller the oil film the more likely there will be metal-to-metal contact and increased wear. It's simple tribology.

People think just because the engine didn't blow-up that everything must be fine, but people have no real accurate way to know if their engine is slowly wearing out faster by using a thinner oil. I'm talking about the hot viscosity, not the cold "W" viscosity. Of course no engine technically really needs anything above a 0W for cold start-up.

But the W rating can have an impact on the hot viscosity charactgeristics. For instance, a 10W-30 vs a 5W-30 will have a slightly better HTHS, and will most likely also have better shear viscosity above the standard 1M/sec shear rate due to less VIIs.
 
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You're missing the point.

I can't say I would reject a 18% pay raise, but... I don't know, that's not a huge difference in the grand scheme of oil viscosities IMO.

I was mainly talking about the different W's, and how 0w is better than other W's.
I’m still confused as to how a particular winter rating is better than a other, isolated from your expected starting temperature.
 
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Go blast it around a track for while with that 0W-20 to get the oil temperature to 250+ F for an extended time and let us know how it goes. Any car driven mellow 99%+ of the time on the street will not "blow-up" going down an oil grade. But how do you know you are not causing more wear by using a thinner oil. Technical studies certainly do show that thinner oil can cause more wear on certain engine components. Thinner oil viscosity reduces the minimum oil film thickness between moving parts, and the smaller the oil film the more likely there will be metal-to-metal contact and increased wear. It's simple tribology.

People think just because the engine didn't blow-up that everything must be fine, but people have no real accurate way to know if their engine is slowly wearing out faster by using a thinner oil. I'm talking about the hot viscosity, not the cold "W" viscosity. Of course no engine technically really needs anything above a 0W for cold start-up.

But the W rating can have an impact on the hot viscosity charactgeristics. For instance, a 10W-30 vs a 5W-30 will have a slightly better HTHS, and will most likely also have better shear viscosity above the standard 1M/sec shear rate due to less VIIs.
Which may not always be correct. Many of us had a love affair with GC back in the day.
 
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