2021 Toyota Supra…been some time…which oil brand & weight?

[supradupra]

If you don't care about the warranty the Rotella T6 is fine. However if anything does goes wrong, you'll be stuck with the bill as it's not a BMW approved oil spec. I'm not disagreeing with you that T6 is a good oil btw, but BMW will never approve any warranty work if they take oil samples.

nothing a spill and fill (or 2 if needed) wont take care of if my a91 starts burning oil....so far 3 guys on the a91 edition FB page have had engine replacements running the stock oil

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[polaris]

You do know how they come up with viscosity numbers right? The numbers are based on flow resistance. The less the resistance (thinner oil) the smaller the number. That meaning if the 100°c # is bigger, it doesnt flow as well, meaning more resistance which equates to a thicker oil.

I can bring up oil temp compared to thermal expansion and what that does to bearing clearance but lets not get there just yet.

I think most people (like me) use "thick" and "thin" as a short hand for "more viscous" and "less viscous". People associate density with flow resistance because that's what intuitively makes sense to them even though it's not really correct. If you really want to split hairs, technically it is true that oil does become thinner (read: less dense) as it gets hot, but obviously not by a significant amount, and it has nothing to do with the flow resistance of the oil.

 

[suicidaleggroll]

I am honestly still baffled that most people think the number in front of the W means "warm".... and that oil "thins" out when it gets warm.

Oil absolutely thins out when warm, the viscosity changes by over an order of magnitude. Have you never done an oil change on a cold car vs a hot car?

https://wiki.anton-paar.com/en/engine-oil/

 

[Evolution]

I think we all have our own meanings for "thick" and "thin" haha. I say it like Polaris described. I say it based off how well it flows.

Eggroll - the way you describe it is how I would say it pours. You take a bottle of Lucas engine stabilizer oil and you cant even pour it when cold. Its like a gel. Warm it up and it turns into a liquid.

Long story short, do we all agree that warm oil is more viscous, doesnt flow as well, once its up to temp?

 

[suicidaleggroll]

I think we all have our own meanings for "thick" and "thin" haha. I say it like Polaris described. I say it based off how well it flows.

That's viscosity

Eggroll - the way you describe it is how I would say it pours. You take a bottle of Lucas engine stabilizer oil and you cant even pour it when cold. Its like a gel. Warm it up and it turns into a liquid.

Again, that's viscosity, same thing.

Long story short, do we all agree that warm oil is more viscous, doesnt flow as well, once its up to temp?

No, the viscosity drops when it warms up, it flows easier, pours easier, thins out, whatever you want to call it. This is backed up by observation from anyone who's done an oil change and the data in the link I posted previously.

 

[outxlove]

I know you didn't want track/performance recommendations but some people might. I use 5w40 as well as a lot of other modified/track oriented supra builds.

I personally use motul 8100 x-cess 5w40 on mine (Pure 800 + most other normal bolt ons).

 

[Evolution]

No, the viscosity drops when it warms up, it flows easier, pours easier, thins out, whatever you want to call it. This is backed up by observation from anyone who's done an oil change and the data in the link I posted previously.

Do you agree that the numbers on oil bottles are viscosity ratings? If so, then the viscosity goes up when the oil gets warm.

The article you posted shows kinematic viscosity. I am talking about dynamic viscosity since we are talking about an engine that makes oil psi, not static flow under no pressure. Your oil change example is a perfect example of kinematic viscosity vs temp.

 

[suicidaleggroll]

The article you posted shows kinematic viscosity. I am talking about dynamic viscosity

It shows both, adjacent columns, they show the same behavior.

Do you agree that the numbers on oil bottles are viscosity ratings? If so, then the viscosity goes up when the oil gets warm.

No, it doesn't. Take a 30 weight oil (no winter rating, just straight SAE 30), it will have a viscosity of say 1000 when cold and 10 when hot. Now take a 0 weight oil (no winter rating, just straight SAE 0), it will have a viscosity of say 500 when cold when cold and 5 when hot.

Now take a 0W30 oil, it will have roughly a viscosity of 500 when cold, and 10 when hot. When it's cold it has the viscosity of a cold SAE 0, and when it's hot it has the viscosity of a hot SAE 30, but a hot SAE 30 is still less viscous than a cold SAE 0.

It's still oil, it's still thinner/less viscous when hot than it is when cold, the difference between the cold/hot viscosity is just smaller than it would be if you were running a straight SAE oil, that's what the "winter" additives give you. They don't somehow reverse the fundamental relationship between temperature and viscosity that all oils have.

 

[Evolution]

It shows both, adjacent columns, they show the same behavior.


No, it doesn't. Take a 30 weight oil (no winter rating, just straight SAE 30), it will have a viscosity of say 1000 when cold and 10 when hot. Now take a 0 weight oil (no winter rating, just straight SAE 0), it will have a viscosity of say 500 when cold when cold and 5 when hot.

Now take a 0W30 oil, it will have roughly a viscosity of 500 when cold, and 10 when hot. When it's cold it has the viscosity of a cold SAE 0, and when it's hot it has the viscosity of a hot SAE 30, but a hot SAE 30 is still less viscous than a cold SAE 0.

It's still oil, it's still thinner/less viscous when hot than it is when cold, the difference between the cold/hot viscosity is just smaller than it would be if you were running a straight SAE oil, that's what the "winter" additives give you. They don't somehow reverse the fundamental relationship between temperature and viscosity that all oils have.

Alright, I am just going to end this here. We arent getting anywhere... I get what you are saying and agree but we are still talking 2 different languages. Honestly, I am horrible at explaining things haha. I will put it like this. You are comparing how fast 2 different oils pour out of a cup. I am comparing those same 2 oils but with how much force it takes to stir with a spoon, if that makes sense.

 

[suicidaleggroll]

You are comparing how fast 2 different oils pour out of a cup. I am comparing those same 2 oils but with how much force it takes to stir with a spoon

That's viscosity, in both cases.

Hot oil is thinner, runnier, easier to pour, easier to flow, easier to stir, and whatever other adjectives you want to use to describe something that's less viscous, than cold oil is.

 

[Bundy]

The preferred oil is 0W20 in Sweden because of their ridiculous EPA policies.

I don´t think the coming generation sees it as ridiculous, only the people sticking their heads in the sand and pretends nothing is happening and all will stay the same.

 

[Bundy]

Papadakis racing for example uses a 5W50, and there's a technical reason for that - less shearing = better engine lubrication.
https://papadakisracing.com/pages/2020-toyota-gr-supra

Totally get that, but that is a 1000+ hp full out race car. I drive a 350 hp sports car. The needs and stresses put on the two cars are not exactly the same to be honest.

 

[digicidal]

Totally get that, but that is a 1000+ hp full out race car. I drive a 350 hp sports car. The needs and stresses put on the two cars are not exactly the same to be honest.

Exactly! Not even close... since it's a drift car it probably spends more time bouncing off the rev-limiter in a single run than a "normal race car" sees in an entire day... and a street car sees in it's lifetime (certainly mine).

Additionally most of that stress is without any benefit of airflow beyond what the fans provide since it's moving sideways as much as possible while doing it.

Not even apples to oranges... more like apples to artichokes.

 

[bajanstefan]

Exactly! Not even close... since it's a drift car it probably spends more time bouncing off the rev-limiter in a single run than a "normal race car" sees in an entire day... and a street car sees in it's lifetime (certainly mine).

Additionally most of that stress is without any benefit of airflow beyond what the fans provide since it's moving sideways as much as possible while doing it.

Not even apples to oranges... more like apples to artichokes.

Life gets interesting around the limiter. Not saying to make it a habit but there's enlightenment between 6 and 7000 rpm.

 

[suicidaleggroll]

I don´t think the coming generation sees it as ridiculous, only the people sticking their heads in the sand and pretends nothing is happening and all will stay the same.

It's not that protecting the environment is ridiculous, it's that rules like these make things even worse. What's the environmental impact of burning a quart of oil every 1k miles and destroying the engine every 50k miles, including all of the wasted material and CO2 emissions involved in building/shipping a replacement engine? Compared to a savings of what, 1 mpg highway and even less in the city? It's not worth the tradeoff.

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