Your car's Engine oil

[Egan101]

here's a stupid question :

some people say that 10w40 is recommended for a hot country like PH. but if you monitor your coolant temps via obd2 it's the same max temps of around 86c whether you're in baguio in january, or in dagupan city in the summer.

so what's the point in using thicker oils in PH then, if the cooling system is able to regulate the temps anyway

These people maybe don’t even read the manuals of their vehicles. There is a reason manufacturers indicate the specific type of lubricant for their engines.

There are far worse regions with a hotter climate compared to PH.


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[Vodka]

These people maybe don’t even read the manuals of their vehicles. There is a reason manufacturers indicate the specific type of lubricant for their engines.

There are far worse regions with a hotter climate compared to PH.


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well my manual says that you can use 0w16 up to 20w40. pretty wide range of viscosities

and it could be argued that a thicker oil protects better albeit at the expense of fuel economy. so i guess the real reason to use thicker oil is protection, and not some BS reason like hot weather

[oj88]

here's a stupid question :

some people say that 10w40 is recommended for a hot country like PH. but if you monitor your coolant temps via obd2 it's the same max temps of around 86c whether you're in baguio in january, or in dagupan city in the summer.

so what's the point in using thicker oils in PH then, if the cooling system is able to regulate the temps anyway

I've come to learn that it's a fallacy to believe that the coolant temperature represents the engine temperature as a whole.

Understand that the coolant does NOT cool the "whole" engine. The coolant is confined within a relatively small chamber around the cylinders and valve head. What the cooling system is regulating is the combustion chamber temperature around those areas.

But how do you cool the pistons? How do you cool the other parts of the engine (from heat soak)?

I think we can agree that the motor oil does more than just lubricate moving parts as it's also used to cool them. However, the engine oil is not normally or directly cooled by the coolant. They do their job and then allowed to drip down to the sump. It is exposed to very high temperature peaks (ie. spray nozzles cooling the underside of each pistons), lubricating and cooling the turbo, as well as absorbing heat soak from internal parts, journals, bearings, etc. that is not in any way cooled by the coolant. While it's in the sump, it transfers some of the heat to the outside world.

So while the coolant enjoys the benefit of a radiator to dissipate heat, your engine oil does not. In fact, oil coolers are sometimes installed on certain vehicles that may experience particularly heavy load conditions. That said, ambient temperature is still very much relevant in choosing the correct viscosity. Cooler ambient temps means lower average oil temps, while the opposite is true.

From what I've gathered, the engine oil can be 20-60°C hotter than the coolant temp (depending on a lot of factors). So it is possible that the coolant temp may show it's at a "nominal" 110°C , the engine oil could be experiencing north of 150°C.

[Dr.Kamiya]

here's a stupid question :

some people say that 10w40 is recommended for a hot country like PH. but if you monitor your coolant temps via obd2 it's the same max temps of around 86c whether you're in baguio in january, or in dagupan city in the summer.

so what's the point in using thicker oils in PH then, if the cooling system is able to regulate the temps anyway

Coolant Temp is NOT Oil Temp

Tracking the car with the same coolant temp I get much higher oil temps on Motul compared to Royal Purple.

From a cold start and just idling the car, the coolant temp goes up pretty quick, but the oil temps might still be low.

Plus even manufacturers recommend thicker oil when the engine is "babad" at higher temps like during racing or track days.

STI for example makes their own high-end oil, which 10W-40 for the street, or 10W-60 for track.



These days I'm averaging the two weights and use HKS 15W-50 or Royal Purple 20W-50

[Vodka]

I've come to learn that it's a fallacy to believe that the coolant temperature represents the engine temperature as a whole.

Understand that the coolant does NOT cool the "whole" engine. The coolant is confined within a relatively small chamber around the cylinders and valve head. What the cooling system is regulating is the combustion chamber temperature around those areas.

But how do you cool the pistons? How do you cool the other parts of the engine (from heat soak)?

I think we can agree that the motor oil does more than just lubricate moving parts as it's also used to cool them. However, the engine oil is not normally or directly cooled by the coolant. They do their job and then allowed to drip down to the sump. It is exposed to very high temperature peaks (ie. spray nozzles cooling the underside of each pistons), lubricating and cooling the turbo, as well as absorbing heat soak from internal parts, journals, bearings, etc. that is not in any way cooled by the coolant. While it's in the sump, it transfers some of the heat to the outside world.

So while the coolant enjoys the benefit of a radiator to dissipate heat, your engine oil does not. In fact, oil coolers are sometimes installed on certain vehicles that may experience particularly heavy load conditions. That said, ambient temperature is still very much relevant in choosing the correct viscosity. Cooler ambient temps means lower average oil temps, while the opposite is true.

From what I've gathered, the engine oil can be 20-60°C hotter than the coolant temp (depending on a lot of factors). So it is possible that the coolant temp may show it's at a "nominal" 110°C , the engine oil could be experiencing north of 150°C.

yeah but engine oil temp is still ultimately dependent on the coolant temp coz the radiator really is the only significant way the engine loses heat (assuming no separate oil cooler). there's a fixed thermal resistance between oil and coolant

so if the cooling system can regulate the coolant temp at a constant 86c (assuming constant load) then we can also expect the oil temp to be a constant X degrees above 86, REGARDLESS of weather conditions in philippines (coz our weather doesn't go above that certain point where the cooling system is unable to regulate the coolant to 86)

[oj88]

yeah but engine oil temp is still ultimately dependent on the coolant temp coz the radiator really is the only significant way the engine loses heat (assuming no separate oil cooler). there's a fixed thermal resistance between oil and coolant

so if the cooling system can regulate the coolant temp at a constant 86c (assuming constant load) then we can also expect the oil temp to be a constant X degrees above 86, REGARDLESS of weather conditions in philippines (coz our weather doesn't go above that certain point where the cooling system is unable to regulate the coolant to 86)

I can't go into the science of it all as I am not an expert but I can cite two things:
1. Oil is typically passively cooled by virtue of the oil sump exposed to the ambient air
2. Entropy, the 2nd law of Thermodynamics. Simply put, something hot will dissipate its energy to something that is cool. The greater the difference in temperature, the more thermal energy can be dumped.

Since the oil spends the longest amount of time in the sump (which also serves as the reservoir), most of the heat the oil has collected is transferred to the sump and in turn, is dissipated to the surrounding air external to the engine. If the ambient air is cold, it will aid in the heat transfer. But when the ambient temp is warm, the process becomes less efficient so the oil continues to soak up the heat.

Even though we're just talking about a few degrees of ambient temperature, it's a big deal to the oil.

Here's why... If you look at the chart below and focus just on the mineral oil, you can see that its theoretical lifespan at 90°C is 3,000 hours. Increasing the oil temperature to 100°C reduced the expected lifespan down to 1,000 hours. Increasing it further to 110°C, the lifespan is now down to just 300 hours.

Putting it another way, raising the oil temp from 90°C to 110°C reduced the useful life of the oil by 90%!

As a side note, the chart also implies that better quality oils, including synthetics, does have an effect on oil life, owing to the fact that they are more temperature-tolerant and less likely to break down from extreme heat. By that logic, this may extend your OCI if you use quality oil. But that's a different topic altogether.

[Vodka]

I can't go into the science of it all as I am not an expert but I can cite two things:
1. Oil is typically passively cooled by virtue of the oil sump exposed to the ambient air
2. Entropy, the 2nd law of Thermodynamics. Simply put, something hot will dissipate its energy to something that is cool. The greater the difference in temperature, the more thermal energy can be dumped.

Since the oil spends the longest amount of time in the sump (which also serves as the reservoir), most of the heat the oil has collected is transferred to the sump and in turn, is dissipated to the surrounding air external to the engine. If the ambient air is cold, it will aid in the heat transfer. But when the ambient temp is warm, the process becomes less efficient so the oil continues to soak up the heat.

Even though we're just talking about a few degrees of ambient temperature, it's a big deal to the oil.

Here's why... If you look at the chart below and focus just on the mineral oil, you can see that its theoretical lifespan at 90°C is 3,000 hours. Increasing the oil temperature to 100°C reduced the expected lifespan down to 1,000 hours. Increasing it further to 110°C, the lifespan is now down to just 300 hours.

Putting it another way, raising the oil temp from 90°C to 110°C reduced the useful life of the oil by 90%!

As a side note, the chart also implies that better quality oils, including synthetics, does have an effect on oil life, owing to the fact that they are more temperature-tolerant and less likely to break down from extreme heat. By that logic, this may extend your OCI if you use quality oil. But that's a different topic altogether.

yes the sump's metal case can lose some heat. but the PC analogy would be a passively-cooled CPU heatsink i.e. fanless, which is a lot less effective than watercooling

i'm definitely not an automotive engineer but i think the primary way that the oil cools is by simply flowing through the same aluminum block that the coolant is flowing through i.e. the oil being hotter simply transfers heat through the aluminum to the coolant



some cars also have a heat exchanger my ford has one you screw the oil filter into it. then coolant flow through those barbs so the heat from the engine oil gets to the coolant

[oj88]

With the combustion happening in that area, I wouldn't think it's cooler than the rest of the engine. Thermal dynamics change depending on what the engine is doing anyway.

The really active way to lower the oil temp is using an oil cooler. But as I've mentioned previously, not many vehicles have them, which is why using the right viscosity for the intended use (ambient temp included) is really important.

[baludoy]

Very interesting recent flow of conversation here. I'm learning a lot [emoji3526]

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[12vdc]

At higher ambient temps, oil runs hotter and becomes thinner.

So a guy running 5W40 at 36'C from Abra could have lower viscosity than a guy from Bagui0 at 19'C using 0W20.

To make it short, If you run an engine at higher ambient temps, it is usually recommended to use higher viscosity so that it does not thin so much affecting the shear/load performance.

[Dr.Kamiya]

Another data point recommending higher viscosity oil when running the engine hard/hot:

The Partnership between Ferrari and Pennzoil | Pennzoil

Ferrari recommends Pennzoil Platinum® Euro 5W-40 and Pennzoil Platinum® Racing 10W-60

[mousemouse]

What do you guys think of more expensive mineral oils? I usually use 10w30 toyota mineral oil at 200+ in the casa but I recently tried going to an independent shop for maintenance. The cheapest mineral oil was the Motul multigrade plus 10w40 at 375/L. I think I could have bought a cheap synthetic online but its more convenient for me to just use what the shop has. The engine sounded more quiet after the PMS but I think that was just from the thicker oil

[dr. d]

What do you guys think of more expensive mineral oils? I usually use 10w30 toyota mineral oil at 200+ in the casa but I recently tried going to an independent shop for maintenance. The cheapest mineral oil was the Motul multigrade plus 10w40 at 375/L. I think I could have bought a cheap synthetic online but its more convenient for me to just use what the shop has. The engine sounded more quiet after the PMS but I think that was just from the thicker oil

i have been using the manufacturer-specified-grade of off-the-shelf petron mineral oils for decades, to no noticeable ill-effect on our cars.
oil + filter change every 5000 km.

[Vodka]

At higher ambient temps, oil runs hotter and becomes thinner.

So a guy running 5W40 at 36'C from Abra could have lower viscosity than a guy from Bagui0 at 19'C using 0W20.

.

are you sure?

that car in abra has a coolant temp of around 86c. same coolant temp for the car in baguio coz the car auto-regulates the temps

so the only difference is that tiny little sump is exposed to a bit warmer air in abra. i'm still not convinced that the ambient temp has a big effect on oil temps inside the sump coz the surface area is so small

[12vdc]

^Oil has direct contact to piston liners, cam, bearings and all the moving parts that needs to be lubed so imagine the heat and amount of shear forces the oil has to handle. Compared to the coolant that only regulate the heat and remains inside the galleys of water jackets no direct contact to the load.

That explains why coolant is not equal to sump temp, if you're still not convinced then install a temp sender in your sump and around the turbo, then drive to Abra and Baguio during the summer. I guess this topic has been discussed over the oil filter thread and extensively discussed over BITOG - just check those sites if you want to know about oils and how they are blended to meet specs of temp, load, wear, etc.

[Vodka]

^Oil has direct contact to piston liners, cam, bearings and all the moving parts that needs to be lubed so imagine the heat and amount of shear forces the oil has to handle. Compared to the coolant that only regulate the heat and remains inside the galleys of water jackets no direct contact to the load.

That explains why coolant is not equal to sump temp, if you're still not convinced then install a temp sender in your sump and around the turbo, then drive to Abra and Baguio during the summer. I guess this topic has been discussed over the oil filter thread and extensively discussed over BITOG - just check those sites if you want to know about oils and how they are blended to meet specs of temp, load, wear, etc.

i never said that coolant temp is equal to oil temp. oil is obviously hotter

here's a post from bitog:

The predicted sump (bulk) oil temperature versus the coolant temperature was shown to be about 18 to 20 degrees C higher for the oil than for the coolant at 2,000 RPM WOT. At 4,000 RPM WOT, the oil sump temperature was about 50 degrees C higher than the coolant temperature. The slope for both RPM ranges was about 0.7 C/C, which means that on the average, the Oil Sump temperature is always 1.2 to 1.43 times higher than the coolant temp. An interesting side-bar of the study was that the bulk oil temperature increased "only" 0.3 C for every 1.0 C increase in ambient (oustside) temperatures.

temp delta between abra and baguio is 17. multiplied by 0.3. oil temp is only hotter by 5 degrees in abra

so my intuition is correct. oil temps are a lot less influenced by ambient temps coz we have modern cooling systems

[12vdc]

5'C is significant. Na discuss na pala sa Bitog.

Sa Sagada na lang pala baka 7'C difference, para hindi din uminit ang ulo sa Baguio traffic.

[Vodka]

5'C is significant. Na discuss na pala sa Bitog.

Sa Sagada na lang pala baka 7'C difference, para hindi din uminit ang ulo sa Baguio traffic.

are you kidding. 5c is nothing. i bet you guys were expecting a 17c difference

assuming oil temp is 120 in baguio. it's only 125 is abra. only 4.1 percent higher, nothing to worry about

[jigeloh]

here's a stupid question :

some people say that 10w40 is recommended for a hot country like PH. but if you monitor your coolant temps via obd2 it's the same max temps of around 86c whether you're in baguio in january, or in dagupan city in the summer.

so what's the point in using thicker oils in PH then, if the cooling system is able to regulate the temps anyway

My montero is fitted with oil catch can, An oil catch can is a canister that is installed into the intake system between the positive crankcase ventilation valve and the intake manifold, and its function is to “catch” excessive amounts of oil that might be present in the intake system before it can enter the cylinders.

Using a 5w30 wt oil. The catch can collected will be greater than 800ml every 5000km.
Using a 15w40 oil, the oil collected is less than 400ml

The pic below is the filter of provent catch can 150 model. Completely draining the oil collected in cut coke 1liter bottle. Oil is 15w40

My opinion, higher climate temp needa higher viscosity oil recommended by the owners manual..

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[thearsenal1205]

Another data point recommending higher viscosity oil when running the engine hard/hot:

The Partnership between Ferrari and Pennzoil | Pennzoil

Diba shell ang iniiendorse ng ferarri? Wala na sila ni shell?

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