Using 0W-20 in a 2025 Corolla?

[Hohn]

I would either use the manufacturer's recommendation, or one grade higher. If manufacturer suggests 5 grade higher in another part of the world, chances are CAFE is not the only difference.

That's not correct. There is a lot of evidence of massive grade difference recommendation in engines with no differences at all.

And when you think about it, it makes perfect sense. Any engine that can use a 20 grade can of course use the 50 grade because the oil that is 20grade at 100C is also a "50 grade" KV100 when the temperature drops 20C.

So it's impossible to design an engine to be satisfactory on 20 grade oils but NOT satisfactory on 50 grades because oils only thicken as they cool and every engine at some point has a colder start with thicker oil.

A 0w-8 at 40C is still roughly twice as thick as a 0w-40 at 100C.

At 110C, a 50 grade is about the same viscosity at a 40 grade at 100C. Which is the same viscosity as a 30 grade at 85C. Which is the same viscosity as a 20 grade at about 77C.

There is always some temperature at which an oil will have the same viscosity as any other oil at any given temperature.

This is really important to remember. But it shows that every engine that has major temperature swings (and they all do) will necessarily have massive viscosity swings in its oils.

Which is why it is all but impossible for an engine specified for 0w-20 to not be OK on 50 grade. Because they engine IS running on a 50 grade (viscosity wise) or thicker until it's nearly completely warm.

Moreover, the condition under which you would need a thinner oil-- high load, hotter temperatures, higher RPM-- will thin a 50 grade down and increase its flow rate and lower its viscosity.

IN terms of engine protection and wear mitigation, a really thick oil is only a detriment during a cold start and only then if sufficiently thick to delay oil pressure beyond 3 seconds or so when started, which can be significantly mitigated by smart EP/AW additizing (moly).

That leaves just the elevated parasitic drag of pumping thicker oil. Which the most minor of downsides, but is the entire rationale for thinner oils.


One will search with much frustration to find any tribological papers showing lower wear with thinner oils in a nominal operating condition. Thicker oils protect better. The only real argument against them is that the extra protection isn't enough to warrant eating a small fuel economy penalty over someone's assume ownership period. If you have a own-nothing-and-be-happy mindset of perpetual leasing, there's no benefit to going much thicker, going only a grade thicker is sufficient.

 

[Hohn]

I might also add, the he benefit of thicker oils tapers off as you go thicker. If you are coming from an oil that's <<3.5 HTHS to one that is 3.5 HTHS, there is a considerable and measurable wear reduction from improved film thickness-- on the order or 25%-30%. The benefit of going thicker than 3.5 continues as you go thicker until it tapers off at around 4.2 HTHS. Once you have 4.2 HTHS, the additional HTHS is only necessary to offset dilution or shearing or other degradations over the service interval.

For example, in the case of my Accord, I figure an HTHS of 4.7 when the oil is virgin is about perfect because it will finish the OCI at around 4.1 even if I have up to 5% dilution. Plus the thicker oil should reduce dilution somewhat.

So my next OCI on the Accord won't we entirely 15w-40 HPL; I will blend it 3:2 with 20w-50 HPL PCMO to give an oil with 4.7 HTHS. This is about "optimal" in my duty cycle and my area with a turbocharged K20C4 using HPL's PCMO was ~600ppm of moly.

If I lived a bit warmer location, I would use HPL 20w-50 entirely and take that massive 5.5 HTHS to the bank.

 

[altaylar]

That's not correct. There is a lot of evidence of massive grade difference recommendation in engines with no differences at all.

And when you think about it, it makes perfect sense. Any engine that can use a 20 grade can of course use the 50 grade because the oil that is 20grade at 100C is also a "50 grade" KV100 when the temperature drops 20C.

So it's impossible to design an engine to be satisfactory on 20 grade oils but NOT satisfactory on 50 grades because oils only thicken as they cool and every engine at some point has a colder start with thicker oil.

A 0w-8 at 40C is still roughly twice as thick as a 0w-40 at 100C.

At 110C, a 50 grade is about the same viscosity at a 40 grade at 100C. Which is the same viscosity as a 30 grade at 85C. Which is the same viscosity as a 20 grade at about 77C.

There is always some temperature at which an oil will have the same viscosity as any other oil at any given temperature.

This is really important to remember. But it shows that every engine that has major temperature swings (and they all do) will necessarily have massive viscosity swings in its oils.

Which is why it is all but impossible for an engine specified for 0w-20 to not be OK on 50 grade. Because they engine IS running on a 50 grade (viscosity wise) or thicker until it's nearly completely warm.

Moreover, the condition under which you would need a thinner oil-- high load, hotter temperatures, higher RPM-- will thin a 50 grade down and increase its flow rate and lower its viscosity.

IN terms of engine protection and wear mitigation, a really thick oil is only a detriment during a cold start and only then if sufficiently thick to delay oil pressure beyond 3 seconds or so when started, which can be significantly mitigated by smart EP/AW additizing (moly).

That leaves just the elevated parasitic drag of pumping thicker oil. Which the most minor of downsides, but is the entire rationale for thinner oils.


One will search with much frustration to find any tribological papers showing lower wear with thinner oils in a nominal operating condition. Thicker oils protect better. The only real argument against them is that the extra protection isn't enough to warrant eating a small fuel economy penalty over someone's assume ownership period. If you have a own-nothing-and-be-happy mindset of perpetual leasing, there's no benefit to going much thicker, going only a grade thicker is sufficient.

I gotta say you have a good point, but the argument is flawed at so many different levels. I used to write longer messages here but i already figured it never helps anyone.

Just 2 points that if you give it to your favorite LLM along with your message, it should be helpful:

1) The "same" engine manufactured in two different geographies is not always made to same margins. Even a location manufacturing for 2 different markets may allocate them to different CNC machines. Using the manual of a different country may not necessarily be your best bet. (i am in no shape or form arguing that manufacturers have no incentive to suggest thinner oil in the USA. I also use 1 or 2 grade thicker oil on 2 of my 5 vehicles)

2) As the engine heats up, materials extend, while gaps shrink (mostly). An engineer ideally needs to optimize for the full spectrum while giving different weights to each micro window, and the lion share goes to the steady state window, which is when your engine is fully warmed up. Unfortunately that tribologist guy:s's YouTube video on GM recommending 0w40 oil taught it wrong to people. There is nothing special about an engine "seeing" a viscosity it was planned to or not. While the engine only spends seconds at each temperature on its way up, it does stay in the operating window for quite a while, so it should be treated accordingly

 

[Revving2Redline]

That's not correct. There is a lot of evidence of massive grade difference recommendation in engines with no differences at all.

And when you think about it, it makes perfect sense. Any engine that can use a 20 grade can of course use the 50 grade because the oil that is 20grade at 100C is also a "50 grade" KV100 when the temperature drops 20C.

So it's impossible to design an engine to be satisfactory on 20 grade oils but NOT satisfactory on 50 grades because oils only thicken as they cool and every engine at some point has a colder start with thicker oil.

A 0w-8 at 40C is still roughly twice as thick as a 0w-40 at 100C.

At 110C, a 50 grade is about the same viscosity at a 40 grade at 100C. Which is the same viscosity as a 30 grade at 85C. Which is the same viscosity as a 20 grade at about 77C.

There is always some temperature at which an oil will have the same viscosity as any other oil at any given temperature.

This is really important to remember. But it shows that every engine that has major temperature swings (and they all do) will necessarily have massive viscosity swings in its oils.

Which is why it is all but impossible for an engine specified for 0w-20 to not be OK on 50 grade. Because they engine IS running on a 50 grade (viscosity wise) or thicker until it's nearly completely warm.

Moreover, the condition under which you would need a thinner oil-- high load, hotter temperatures, higher RPM-- will thin a 50 grade down and increase its flow rate and lower its viscosity.

IN terms of engine protection and wear mitigation, a really thick oil is only a detriment during a cold start and only then if sufficiently thick to delay oil pressure beyond 3 seconds or so when started, which can be significantly mitigated by smart EP/AW additizing (moly).

That leaves just the elevated parasitic drag of pumping thicker oil. Which the most minor of downsides, but is the entire rationale for thinner oils.


One will search with much frustration to find any tribological papers showing lower wear with thinner oils in a nominal operating condition. Thicker oils protect better. The only real argument against them is that the extra protection isn't enough to warrant eating a small fuel economy penalty over someone's assume ownership period. If you have a own-nothing-and-be-happy mindset of perpetual leasing, there's no benefit to going much thicker, going only a grade thicker is sufficient.

I might also add, the he benefit of thicker oils tapers off as you go thicker. If you are coming from an oil that's <<3.5 HTHS to one that is 3.5 HTHS, there is a considerable and measurable wear reduction from improved film thickness-- on the order or 25%-30%. The benefit of going thicker than 3.5 continues as you go thicker until it tapers off at around 4.2 HTHS. Once you have 4.2 HTHS, the additional HTHS is only necessary to offset dilution or shearing or other degradations over the service interval.

For example, in the case of my Accord, I figure an HTHS of 4.7 when the oil is virgin is about perfect because it will finish the OCI at around 4.1 even if I have up to 5% dilution. Plus the thicker oil should reduce dilution somewhat.

So my next OCI on the Accord won't we entirely 15w-40 HPL; I will blend it 3:2 with 20w-50 HPL PCMO to give an oil with 4.7 HTHS. This is about "optimal" in my duty cycle and my area with a turbocharged K20C4 using HPL's PCMO was ~600ppm of moly.

If I lived a bit warmer location, I would use HPL 20w-50 entirely and take that massive 5.5 HTHS to the bank.

Running my K24 9th gen Accord on Valvoline Extended Protection High Mileage 5w30 & Schaeffers 132 so I am surely around the 4 hths. Even this winter Im gonna go Valvoline Restore and Protect 5w30 & try to use up some Redline 0w30 which is 3.3hths.

 

[kschachn]

I gotta say you have a good point, but the argument is flawed at so many different levels. I used to write longer messages here but i already figured it never helps anyone.

Just 2 points that if you give it to your favorite LLM along with your message, it should be helpful:

1) The "same" engine manufactured in two different geographies is not always made to same margins. Even a location manufacturing for 2 different markets may allocate them to different CNC machines. Using the manual of a different country may not necessarily be your best bet. (i am in no shape or form arguing that manufacturers have no incentive to suggest thinner oil in the USA. I also use 1 or 2 grade thicker oil on 2 of my 5 vehicles)

2) As the engine heats up, materials extend, while gaps shrink (mostly). An engineer ideally needs to optimize for the full spectrum while giving different weights to each micro window, and the lion share goes to the steady state window, which is when your engine is fully warmed up. Unfortunately that tribologist guy:s's YouTube video on GM recommending 0w40 oil taught it wrong to people. There is nothing special about an engine "seeing" a viscosity it was planned to or not. While the engine only spends seconds at each temperature on its way up, it does stay in the operating window for quite a while, so it should be treated accordingly

On the other hand, engines are not damaged by an oil with a higher HT/HS, actually quite the opposite. However, they can be damaged by oil with one that is too low.

The bearing clearances are not too small for a higher grade. The whole argument about engines being different in a different region is a nothing burger even if it is somehow true.

Engineers don’t optimize oil grades anymore for modern vehicles. What they do is engineer engines that can tolerate thinner grades without excessive wear so that fuel economy can be obtained. However, this does not in any way preclude the use of a higher grade regardless of somebody’s imagination on the subject.

 

[altaylar]

The whole argument about engines being different in a different region is a nothing burger even if it is somehow true.

Oh you would be surprised

 

[kschachn]

Oh you would be surprised

Surprise me then? Tell me how these differences affect the use of an oil grade. That’s what we were talking about here.

 

[TijY_]

I gotta say you have a good point, but the argument is flawed at so many different levels. I used to write longer messages here but i already figured it never helps anyone.

Just 2 points that if you give it to your favorite LLM along with your message, it should be helpful:

1) The "same" engine manufactured in two different geographies is not always made to same margins. Even a location manufacturing for 2 different markets may allocate them to different CNC machines. Using the manual of a different country may not necessarily be your best bet. (i am in no shape or form arguing that manufacturers have no incentive to suggest thinner oil in the USA. I also use 1 or 2 grade thicker oil on 2 of my 5 vehicles)

2) As the engine heats up, materials extend, while gaps shrink (mostly). An engineer ideally needs to optimize for the full spectrum while giving different weights to each micro window, and the lion share goes to the steady state window, which is when your engine is fully warmed up. Unfortunately that tribologist guy:s's YouTube video on GM recommending 0w40 oil taught it wrong to people. There is nothing special about an engine "seeing" a viscosity it was planned to or not. While the engine only spends seconds at each temperature on its way up, it does stay in the operating window for quite a while, so it should be treated accordingly

1. Is speculation, but sure might have some validity in some edge cases.
The problem is that they would never solve the logistics to ensure that either engine plants engine does not end up in the U.S or vice versa.

 

[altaylar]

1. Is speculation, but sure might have some validity in some edge cases.
The problem is that they would never solve the logistics to ensure that either engine plants engine does not end up in the U.S.

I am not sure what you meant for logistics here. We used to ship them in different containers to different countries. But if you mean they whether they later cross ship them to meet a demand shock, i actually don't have an information.

Edit: maybe you meant for the models that are made at a single location for the whole world. In in those cases crates were labeled clearly, and critical.components marked, which would be erased in the plant of assembly. We shipped them at different dates, and industry is very reliant on Just in time manufacturing, so contamination does not seem too likely, but you are right, one can never be sure.

 

[TijY_]

But if you mean they whether they later cross ship them to meet a demand shock, i actually don't have an information.

That. Any unexpected downtime or scheduled downtime and voila X amounts of units will be shipped from the other plant.

 

[altaylar]

That. Any unexpected downtime or scheduled downtime and voila X amounts of units will be shipped from the other plant.

I don't know how likely is that happen due to supply side shocks. Even in those cases, I guess it would be more likely to adhere to targeted market's designation.

An easy way to check would be the charcoal filters. In my GR86 there is one, but most other countries don't have one. Now i wonder if anyone in the usa received one without the Charcoal filter, or anyone elsewhere received one with it

 

[TijY_]

I don't know how likely is that happen due to supply side shocks. Even in those cases, I guess it would be more likely to adhere to targeted market's designation.

An easy way to check would be the charcoal filters. In my GR86 there is one, but most other countries don't have one. Now i wonder if anyone in the usa received one without the Charcoal filter, or anyone elsewhere received one with it

I fail to see the relevance.

I work in vehicle manufacturing, we send and receive support shipments weekly. From and to South America, Asia and Europe.

 

[kschachn]

I fail to see the relevance.

Especially in regards to how one of those engines would somehow require the use of a lower viscosity oil.

 

[altaylar]

I fail to see the relevance.

What I was thinking there is, if US production was contaminated with Non-US production on the airfilter housing, you could easily find that out later when you are changing the airfilter on this particular car.

I work in vehicle manufacturing, we send and receive support shipments weekly. From and to South America, Asia and Europe.

You definitely do have a different vantage point here. I worked at engine part manufacturing, so I don`t really know how those support shipments work at your end

 

[TijY_]

What I was thinking there is, if US production was contaminated with Non-US production on the airfilter housing, you could easily find that out later when you are changing the airfilter on this particular car.

You definitely do have a different vantage point here. I worked at engine part manufacturing, so I don`t really know how those support shipments work at your end

See it like this. Would you spend XXX of millions setting up manufacturing on another continent. And then produce it not being interchangeable... ?
I don't know a single company who would do that.

There is no target market or contamination. It is locally produced or not.
Edit: assuming they have the same engine code.

 

[Urshurak776]

Why would you want to do that? Has it ocurred to you that Toyota has millions upon millions of miles of real world testing behind that 0w-8 reccomendation?

If it really bothers you then perhaps a 0w-16 is in order. It's not as if you have extreme heat to deal with in NJ.

I think the real purpose of that testing is to see how long the engine will last when we make compromises due to CAFE requirements.

Toyota wants you to buy a new car every 5 years or so, which is why we (the consumer) are NOT in their best interest when they test oil viscosity. Car has to get through warranty, then they want you back at Dealership with your checkbook. This way, you can buy the new car that takes 0w-5 oil. Start the cycle again.

 

[altaylar]

See it like this. Would you spend XXX of millions setting up manufacturing on another continent. And then don't produce it to be interchangeable... ?

I don't know a single company who would do that.

There is no target market or contamination. It is locally produced or not.

I am not sure if I am following you here. I know 3 firms that used what I would call "different quality" of components depending on the market they were serving.

An example would be that I can share is from Tesla. They use different battery chemistry depending on the manufacturing site.: https://www.electrive.com/2023/05/0...y-using-byd-batteries/?utm_source=chatgpt.com

 

[TijY_]

I am not sure if I am following you here. I know 3 firms that used what I would call "different quality" of components depending on the market they were serving.

An example would be that I can share is from Tesla. They use different battery chemistry depending on the manufacturing site.: https://www.electrive.com/2023/05/0...y-using-byd-batteries/?utm_source=chatgpt.com

I bet if you ask Tesla they are of the same quality. And the finished battery packs are more then likely interchangeable.
If they are not they would have a different "engine code" (battery pack code).

And again I fail hard to see the relevance.

 

[altaylar]

I bet if you ask Tesla they are of the same quality. And the finished battery packs are more then likely interchangeable.
If they are not they would have a different "engine code" (battery pack code).

And again I fail hard to see the relevance.

Did I say they would not be interchangeable?

 

[altaylar]

Just to recap, i was not saying a piece made for one would not fit into another. But the quality of machining or tolerance to casting imperfections can certainly be different, which is relevant for oil suggestion