Your Opinion on Choosing an Oil Grade

[BrendanC]

Which sort of raises the question as to whether we should all install oil coolers so we can run thinner oils and still have them be thicker in the engine, eh?

i have coolant to oil heat exchangers on all three of my vehicles. it helps my oil warm up faster in the morning and helps it stay closer to coolant temps. however, i run thicker oil than spec in all of them. 5w-40 in my car/truck and 5w-30 in the wife’s accord.
truck calls for 5w-30
honda’s call for 5w-20.

 

[Hohn]

I read it, and I understand what you were trying to say, but it still made no sense. You can't command your oil to stay at a lower temperature so its thicker.

So why are race teams adding oil coolers? Are they worried about oxidation shortening their drain interval? Perhaps intake valve deposits due to volatility in a GDI engine? Of course not. It's viscosity and only viscosity that causes them to use oil coolers. The concern is a loss of viscosity and a loss of oil pressure and nothing else. There's simply no other reason to care about oil temps in a race engine.

It's the exact same dynamic in a street engine , just moved down to lower temperatures and oils with a lower KV100.

Your engine oil temp is going to be what its going to be under any given use,

Not true.

hence a 30 weight oil will always have a higher viscosity than a 20 weight oil at the same temp.

True but non sequitur. Yes, the 30 grade always has a higher viscosity at the same temp, but it's not the same temp unless you want to argue that adding an oil cooler has no effect on oil temps.

 

[SC Maintenance]

So why are race teams adding oil coolers?

This thread is not about adding oil coolers. Wrong thread, wrong sub-forum. But since you brought it up - oil lubrication properties start to degrade quickly above 250F, which is why most race engines run cooler.

Not true.

Most modern cars use constant volume oil pumps that spend most of their time running oil through a bypass and back into the pan. So yes, in practical terms it is.

Yes, the 30 grade always has a higher viscosity at the same temp, but it's not the same temp unless you want to argue that adding an oil cooler has no effect on oil temps.

Again, your the only one talking about oil coolers. My current model rav4 doesn't even have an engine oil cooler.

 

[Hohn]

i have coolant to oil heat exchangers on all three of my vehicles. it helps my oil warm up faster in the morning and helps it stay closer to coolant temps. however, i run thicker oil than spec in all of them. 5w-40 in my car/truck and 5w-30 in the wife’s accord.
truck calls for 5w-30
honda’s call for 5w-20.

Have you logged oil temps vs coolant temps?

Are you sure the warmup heat is flowing from coolant to oil and not from oil to coolant?

 

[BrendanC]

Have you logged oil temps vs coolant temps?

Are you sure the warmup heat is flowing from coolant to oil and not from oil to coolant?

i don’t have oil temperature sensors in any of them. i can feel the temperature delta on the hoses going to the exchangers on my accords so i do know it is warming the oil.

 

[OilUzer]

They call it heath exchanger because it works two ways and it's not one directional. Otherwise they would call it heater or cooler.

When the engine is cold or very cold i.e. on very cold days or winter, the coolant/water warms up the engine (or transmission) oil and it runs hotter than oil initially. Once the engine has warned up or under heavy load, it is the reverse meaning the engine oil will be hotter than coolant and the exchange is reversed. That is why it's called exchanger.

btw, I have monitored all (engine oil, water, trans oil and intake temps, etc.) with OBD-II apps & scanners and it also depends on where the sensors are located hence some variation in readings with different cars, but in general that's the concept of the heat exchanger ... but I am willing to learn something new. Lol

 

[Hohn]

They call it heath exchanger because it works two ways and it's not one directional. Otherwise they would call it heater or cooler.

When the engine is cold or very cold i.e. on very cold days or winter, the coolant/water warms up the engine (or transmission) oil and it runs hotter than oil initially. Once the engine has warned up or under heavy load, it is the reverse meaning the engine oil will be hotter than coolant and the exchange is reversed. That is why it's called exchanger.

btw, I have monitored all (engine oil, water, trans oil and intake temps, etc.) with OBD-II apps & scanners and it also depends on where the sensors are located hence some variation in readings with different cars, but in general that's the concept of the heat exchanger ... but I am willing to learn something new. Lol

Heat exchanger is a generic term and doesn't necessarily imply bidirectional heat flow in use. A radiator is a heat exchanger even though it essentially never warms the coolant.

 

[crashz]

The poor OP is hiding under a rock right now...

Most people mentioned this, but that Camry will be fine on anything. Don't overthink it too much. Use the HPL or Mobil 1 or Amsoil. Or Supertech. Whatever you like.

I won't jump in too far in the above argument, but to say that oil temps are constant is wrong. They change based on driving style, freeway versus in-town, oil viscosity, rpm, and load. We have a car with an oil temp gauge that sits on the top of the dash (sort of in your face). The above situations have a noticeable affect on the oil temps. Are they going to change the world? No.

 

[OilUzer]

Heat exchanger is a generic term and doesn't necessarily imply bidirectional heat flow in use. A radiator is a heat exchanger even though it essentially never warms the coolant.

If I torched my radiator, then it would warm the coolant. No?
Or if I put my radiator in hell, I'm sure it would boil the coolant.
but what does that have to do with anything?

If one side is always hotter than the other side, the heat transfer will always be one directional but that's not the case with the heat exchangers running two different fluids (e.g. Coolant/ATF heat exchanger or Coolant/Engine oil heat exchanger) with different temperatures.

So there will always be bidirectional heat transfer as long as the fluids are at different temperatures. And we are not talking about the effectiveness of such heat transfer so please don't change the subject.

 

[FlyingTexan]

The Toyota A25A and M20 engines have been out since 2018 with 0W16. No known bearing issues thus far. Appears Toyota got the design right.

Have you tried google? You're picking a small underwhelming engine but it's still had it's issues.

 

[FlyingTexan]

If a manufacturer isn’t recommending a suitable (good enough) oil then there are two options: update the design accordingly or recommend something else. It’s a simple concept. They can adapt or perish.

Then they'd stick with the proven designs that already get 500k miles. But they didn't. Their "upgraded" and "better" designs are currently sitting there with factory recalls.

 

[FlyingTexan]

How exactly does one shear the oil with “high output”?

Viscosity loss due to mechanical stress' on the engine.

https://shopmotul.com/what-is-oil-s...ngines,can accelerate the degradation process.

 

[Hohn]

Viscosity loss due to mechanical stress' on the engine.

https://shopmotul.com/what-is-oil-shearing-and-why-does-it-matter/#:~:text=Common Causes of Oil Shearing in Automotive Engines&text=High-performance engines, turbocharged engines,can accelerate the degradation process.

”mechanical stress” is too vague a term to be useful here. Oils don’t see “mechanical stress”, they see fluid stress. And oil just sees displacement per unit time, essentially. The oil was one place, now it’s being pushed somewhere else, sometimes rather slowly and steadily (say, a piston oil cooler nozzle), sometimes quite violently (say, the top part of a rod bearing when the combustion event occurs) The work involve to make this happen and the time derivative of it is essentially the rate of stress.

And because of how viscosity is defined, the “thicker” an oil is, the greater the shear stress is for the same flow.

Every viscosity spec is at all times a compromise because there’s always a part of the engine that wants more viscosity and another part that wants less.

 

[FlyingTexan]

”mechanical stress” is too vague a term to be useful here. Oils don’t see “mechanical stress”, they see fluid stress. And oil just sees displacement per unit time, essentially. The oil was one place, now it’s being pushed somewhere else, sometimes rather slowly and steadily (say, a piston oil cooler nozzle), sometimes quite violently (say, the top part of a rod bearing when the combustion event occurs) The work involve to make this happen and the time derivative of it is essentially the rate of stress.

And because of how viscosity is defined, the “thicker” an oil is, the greater the shear stress is for the same flow.

Every viscosity spec is at all times a compromise because there’s always a part of the engine that wants more viscosity and another part that wants less.

I suggest you write Motul and explain to them then.

 

[ATex7239]

Have you tried google? You're picking a small underwhelming engine but it's still had it's issues.

I have. And I own one. Nothing is without “issues” but it’s a reliable design thus far.

 

[Hohn]

I suggest you write Motul and explain to them then.

It's a marketing document, not a technical document, is my point. It shouldn't be cited in a technical discussion.

 

[FlyingTexan]

It's a marketing document, not a technical document, is my point. It shouldn't be cited in a technical discussion.

So you won’t accept a statement from an oil company on the properties of oil. What sources will you accept?

 

[Overfill]

Most modern cars use constant volume oil pumps that spend most of their time running oil through a bypass and back into the pan.

really?