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

[Jackson_Slugger]

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.

As far as Mobil 1 EP/AN/TSUV, they tend to use more PAO with up 70%, so it's not just VM...

 

[Just a civilian pilot]

There are numerous discussions on 5W20 vs. 0W20 motor oil. It seems to me that the common consensus is that 0W20 is better than 5W20 for engine lubrication, at least not worse, for oils of the same brand.

What has puzzled me is why some cars (slightly older models) call for 5W20 in their user's manuals, not 0W20? I suspect (in another thread) it was due to availability and price sometime ago, but never get it explained or confirmed. Hope someone can give a more concrete answer.

I sent an email to Honda for their Gen 2 Odyssey, but got a useless answer something like "Our engineering team determined that 5W20 is the oil you should use".

I sent a letter ( 1997 ) to Honda Canada asking them if I could use 0w30 instead of the spec‘d 5w30 in my 1996 Civic ( no BITOG back then ) and they said “no”. They gave me the same answer you got except they did say they were studying the suitability of “0” oils IIRC. Their answer made me nervous ( warranty ) but I put in ( Amsoil ) 0w30 in anyways ( took the labels off when bringing it to dealership ). Thanks to knowledge BITOG, when my next car said to only use 5w20, I put in 0w20 with confidence ( warranty ) once it was available But felt confident enough to keep the labels on and tell them to put it in. 99% of people in dealerships don’t have a clue about engine oil unless they are an enthusiast.

How enlightened their engineers are today, pretty sure new Honda’s come ( Toyota does ) with 0w16 ( it’s safe I am sure but I would run 0w20 , it’s just as safe, and efficient ).

Honda used to spec just motor oil for their manual transmissions.

 

[javacontour]

As we've noted in other cases, sometimes car makers recommend different oils for different nations.

My 2012 Mazda3 recommends 5W20 in Mexico and says if you cannot get it, use 5W30.

 

[javacontour]

So that leftover bottle of 5W20 I have is likely going into the Mazda3 along with the other 4.5 quarts of 0W20 in a couple of months when my next OC is due at 135k miles.

Don't really have anything that calls for 5W20 since my daughter traded her Escape for a Prius. The old 2010 Altima still calls for 5W30 so I keep that on hand for my son.

About the time we get it down to just one, someone will buy a car that takes 0W16, LOL.

 

[Just a civilian pilot]

I have one car that allows 5W20, 5W30 and 10W30 and no mention of 0W20 and have another car that says 0W20 only and says use 5W20 if 0W20 is not available but change back to 0W20 quickly or next time.

Assuming that 5W meets the cold temp spec. so there is no technical reason to select 0W over 5W:

One reason could be the OCI. I think the longer the recommended oci, the more chances of 0W-20 being specified since you can formulate a more inferior 5W20 (e.g. blend) but it's hard(er) to make an inferior or "cheap oil" with 0W20 which has a superior base oil. So the longer the oci, the more of "synthetic" oil requirements (i.e 0W).

price diff between 0 and 5W could have been another reason in older days but it may no longer be an issue. So if the recommended oci is shorter, there is no need for pricier 0W.

Some say 5W20 has less vii and it's better ... I rather take 0W20 with naturally higher vi than risk it with some potentially inferior 5W blend.

I've also read that some designers (old-timers?) prefer less of a pao, ester or higher group oils and prefer more of lower group (III) oils or "syn-blend" as they are more seal friendly, etc. ... This is just a wild guess and something I've read here and there on the internet. Not sure if I believe it 100%

Basically I think oci maybe the main factor. I am a thickie and like oils with less spread but in this case, if I had to use a 20, I would never use 5W20. However, I don't mind using 0W20 even though it has a larger spread.

I think your right about the OCI part being part of the reason. My 2006 Civic ( first Civic to have MM ) would tell me to change the oil every 7500 miles but my next Civic spec’d 0w20 ( pretty sure the 2006 said to use 5w20 ) and all of a sudden the MM would tell me to change it every 12,000 miles ( exact same driving ). Maybe somebody who owns a 2006 Civic here can chime in, pretty sure it took 5w20.

 

[wpod]

5W-20 is the better oil consensus or not.

 

[circuitsmith]

Don't really have anything that calls for 5W20 since my daughter traded her Escape for a Prius. The old 2010 Altima still calls for 5W30 so I keep that on hand for my son.

I would just put 5w-30 in everything.

 

[SunnySky]

No. Only if you are below the gelling temperature of the oil and it causes the pump to cavitate. That would be somewhere below -35F.

It's a common misconception on the Internet that "most wear occurs at startup", typically because it sounds like it should be so. There are some pretty long threads on here discussing that, look for the ones where user Shannow was a contributor.

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.

 

[PimTac]

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.

I would take anything from YouTube with a ton of salt. The only exception would be videos from reliable sources like oil companies for example.

I seriously doubt it takes tens of seconds for oil to reach everywhere in a engine.

 

[SunnySky]

As we've noted in other cases, sometimes car makers recommend different oils for different nations.

My 2012 Mazda3 recommends 5W20 in Mexico and says if you cannot get it, use 5W30.

View attachment 48601

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?

 

[SunnySky]

I would take anything from YouTube with a ton of salt. The only exception would be videos from reliable sources like oil companies for example.

I seriously doubt it takes tens of seconds for oil to reach everywhere in a engine.

Please take a look at this one at 1:50.

 

[OVERKILL]

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.

He's posted plenty of supportive material, keep reading.

The link you just posted has some valuable notes on this:

It’s widely acknowledged by automotive engineers that most engine wear occurs within this first ten minutes of driving before the engine has reached its highest, normal operating temperature.

Studies in laboratory engines equipped with radioactive piston rings show that wear is highest during a cold startup. Corrosion by condensed combustion products is responsible. Engine operating variables and additives in fuels and motor oils influence corrosion and, therefore, startup wear. Long shutdown periods, low engine temperature, and high intake-air humidity increase wear. In fuels, antirusts offer some control; for example, an amine dialkyl phosphate eliminates 40% of the wear.

Note that viscosity is not called out in either of those quotes and that the timeframe is not just the start-up of the engine, where the oil flow angle is necessarily focused, but for a significant duration, long, LONG after full oil flow has been established.

There are several factors in play, one being corrosion caused by the interactions taking place in a cold bore, as noted, and another being reduced ring seal and piston roundness as these parts are still cold and have not expanded to their operating dimensions as of yet. This leads to increased blow-by, oil contamination and of course wear.

It really should be called warm-up wear, as there's a curve where, as the engine warms, wear tapers off as everything comes up to operating temperature and parts reach their operating dimensions, the heat activated additives start working, ring seal improves, blow-by reduces, enrichment tapers off...etc.

 

[PimTac]

Please take a look at this one at 1:50.

Linking like that gives the wrong impression. It’s better to share the link like this.

 

[SunnySky]

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?

 

[SunnySky]

Linking like that gives the wrong impression. It’s better to share the link like this.

Here you go...

 

[Portobelly]

Maybe the 5W is less expensive for the manufacturer to put in the engine as factory fill.

 

[PimTac]

Here you go...

Okay but who is he?

I can start my own YT channel and make videos too.

 

[ka9mnx]

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?

Short answers:
1. You can (I am)
2. No
End of discussion...

 

[SunnySky]

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?

To rephrase my question, What can go wrong if I use a quality 0W20 in a car that calls for 5W20?

 

[ammolab]

Maybe the 5W is less expensive for the manufacturer to put in the engine as factory fill.

This and their dealer network can use a 5W-20 syn blend
0W-20 oils are synthetics