Why do some cars call for 5W20, not 0W20?

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Maybe that is because Mexico is warmer? But still, if 0W works in a cold place, it should work in a warmer place too. Or maybe 0W20 is more expensive than 5W20 in Maxico?
My guess is it is less readily available. I suspect the market for oil in MX leans more towards the 10W30, 10W40 and 20W50 with enough demand for 5W30 to justify stocking it.

But that's just spitballing, I have no experience other than what I've seen in other warm climates.
 

OVERKILL

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Thank everybody for the discussion. Looks like it is disputable whether 0W is more beneficial than 5W, but it is kind of off topic.

My question was/is why cannot we use 0W20 instead of 5W20? Is there any drawback to use 0W20 to replace 5W20 from an engineering point of view?

You can. Mobil recommends their 0w-20 for everywhere a 5w-20 is called for. I'm using a 0w-20 in my wife's truck.
 
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Thank you for pointing me to Shannow's posts. It looks like he/she is a frequent contributor to this forum, while I rarely visit here until recently. Apologize in advance if my posts ignore/offend anyone due to my lack of reading history in this forum.

In the few posts I have read, Shannow discounts the severity of startup wear by attributing sufficient residual oil on the surfaces and at the interfaces. He/she also states that it will take about the same amount of time for oil to reach to important interfaces regardless of oil grade during startup. What is missing for me is the lack of quantitative backup in those posts.

On the other hand, some video on Youtube claims it will take tens of seconds for oil to reach to all the interfaces. The dominant contribution of cold startup wear is also discussed extensively online such as this one.

Not to start a dispute, just try to understand.
The amount of time it takes for the oil to reach critical interfaces is essentially the same. Again, as long as the oil's winter rating is appropriate for the starting conditions the oil will pump.

What's happening in the pressurized system that supplies the bearings and other critical interfaces is not what's being shown in those videos. They also like to illustrate oils that have an inappropriate winter rating.
 
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xW-y spread is y minus x.
For example 5W-20 spread is 15 as opposed to 20 for 0W-20.

Typically the higher the spread, the more viscosity modifier (viscosity index improver) is added to the oil.
Not asking OilUzer specifically, asking anyone who has experience with this subject: I thought I had read in the past that keeping this "spread" number as low as possible (within the specs in the owner's manual) was desirable. Is this no longer the case?
 
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Not asking OilUzer specifically, asking anyone who has experience with this subject: I thought I had read in the past that keeping this number as low as possible (within the specs in the owner's manual) was desirable. Is this no longer the case?
"As thin as possible and as think as necessary." Quoted from numerous sources.
 
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Not asking OilUzer specifically, asking anyone who has experience with this subject: I thought I had read in the past that keeping this "spread" number as low as possible (within the specs in the owner's manual) was desirable. Is this no longer the case?


As far as I know that started back when problems appeared using 10w40 way back when. The oil companies reformulated and it went away but the impact definitely turned a lot of people off of 10w40. One specific brand had the most problems with oil gelling.


I would think that is all behind us as this was a long long time ago.
 
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I would just put 5w-30 in everything.
This is what happens at our place in gas powered vehicles, except motorcycles. They all get 5W30 Mobil 1 synthetic, including my 2008 Honda Fit, company Vehicles, lawn mowers, generators, and more. Diesel engines All get 10W40 Mobil for diesels, Dads truck, Caterpillar loaders, semi trucks, welder, excavators, bulldozer, they all get the same thing. My cars oil cap says 5w20, it got 5w30 anyway. How many people actually would start their car at -35 if not in a garage or plugged in. We don't get even close to that cold here, but if it did, my car would be inside, or at least plugged in.
 

SunnySky

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I'd like to thank everybody's participation in the discussion of "Why do some cars call for 5W20, not 0W20". Somehow along the line the discussion was shifted to "Is 0W20 better than 5W20 for startup wear". Sorry for the drift.

Based on the discussion, I'd conclude this thread as follows:

A quality 0W20 can be used to replace 5W20 categorically, and automobile manufacturers don't have any good engineering reason to call for 5W20 instead of 0W20.

Along that line, I would like to infer that any multigrade oil can be replaced by another multigrade oil with a lower winter grade and same summer grade, as long as they are from quality brands (similar or better additives).
 
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Along that line, I would like to infer that any multigrade oil can be replaced by another multigrade oil with a lower winter grade and same summer grade, as long as they are from quality brands (similar or better additives).
Except really no one knows what are similar or better additives. If you were to state "equal approvals, standards or licenses" then yes.

A PDS or a VOA/UOA does not list additives, it gives a list of decomposed metallic compounds. And with the things the way they are today (trying to reduce ash for example) the VOA/UOA method of reading the "quality" tea leaves is becoming even less relevant.
 

ZeeOSix

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You mean try to save a half pint of fuel over 20K miles of driving? lol
Sure ... it's that 0.0001% better fuel mileage for CAFE which manufacturers are splitting hairs over. Using thinner oil (including during start-up) is an easy hair to split.
 

ZeeOSix

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I seriously doubt it takes tens of seconds for oil to reach everywhere in a engine.
Depends on the temperature and the oil used. Been quite of few discussions here on BITOG showing studies with measured times for oil to get to various regions of engines. When the pumpability of the oil becomes degraded due to temperature, then the times can become pretty long.
 

ZeeOSix

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ZeeOSix

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My question was/is why cannot we use 0W20 instead of 5W20? Is there any drawback to use 0W20 to replace 5W20 from an engineering point of view?
I see no reason not to use 0W-20 in place of 5W-20. 0W and 5W when cold are still thicker than 20 weight when hot.
 
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