Euro oil spec thats better than dexos 1/r?

[kschachn]

I don't have a particular affinity for dexos or a hatred for Euro. I don't like crossing the streams with unverifiable claims.

There it is. The cheat code. You're going to exceed warranty period with Euro oil. You could probably do that with Rotella T4 in a well-built engine.

Why are people clutching their pearls with that part in bold? Those 6.2's fail because 0w-20 didn't provide adequate oil pressure. That's the only reason for a change in viscosity. Viscosity doesn't necessarily mean protection. It only does when there's too much heat or clearances.

Engines aren't engines. Oils aren't oils. Spec matters.

One thing that comes to mind is that you don't fill in a hole you've dug by digging it deeper.

But it can be entertaining.

 

[OVERKILL]

I don't have a particular affinity for dexos or a hatred for Euro. I don't like crossing the streams with unverifiable claims.

There it is. The cheat code. You're going to exceed warranty period with Euro oil. You could probably do that with Rotella T4 in a well-built engine.

Why are people clutching their pearls with that part in bold? Those 6.2's fail because 0w-20 didn't provide adequate oil pressure. That's the only reason for a change in viscosity. Viscosity doesn't necessarily mean protection. It only does when there's too much heat or clearances.

Engines aren't engines. Oils aren't oils. Spec matters.

Again, that addresses none of the points I've made.

 

[chris719]

Yes, they are such meticulous engineers to have crafted the dexos specs and then sold 800k engines with inadequate oil pressure (or is it load/HTHS?) using said spec.

Sometimes the engineers know exactly what they are doing, but sometimes things are just plain dumb.

 

[BMWTurboDzl]

Yes, they are such meticulous engineers to have crafted the dexos specs and then sold 800k engines with inadequate oil pressure (or is it load/HTHS?) using said spec.

Sometimes the engineers know exactly what they are doing, but sometimes things are just plain dumb.

It's being blamed as a manufacturing defect out of Mexico. Inadequate viscosity isn't the problem.

Post in thread 'GM aborting move to 0w-40' https://bobistheoilguy.com/forums/threads/gm-aborting-move-to-0w-40.395438/post-7245609

 

[ZeeOSix]

If a heavier oil, such as an A40 spec 0w-40 or 5w-40, is used that could be problematic. The oil pump has a pressure regulator. If pressure rises too high then the bypass spring opens to hold set pressure. There will be a higher volume of oil pumped to the system for the lower viscosity oil for the same pressure. Therefore, in this instance, C20 protects this engine better than A40 by providing the specified volume of oil for adequate cooling..

What are the details on this oil pump pressure regulating system? You used the words "bypass spring opens to hold set pressure", so that sounds like an old fashioned mechanically controlled pressure regulation valve in the oil pump. If that is the case, then oil pumps like that will be in some stage of pressure and volume regulation around 2000 to 3000 RPM, which means the pump is putting out much more oil flow than the oiling system can flow before the pump starts regulating output pressure. They also keep slowly increasing output pressure and flow as RPM increases, meaning they don't quite regulate the output perfectly once in regulation. In a system like that, it really doesn't matter if the oil is a xW-16 to a xW-50 because the pump (if sized correctly) at a relatively low RPM is trying to forcing much more oil through the system than what the minimum flow would be needed to adequately lubricate the engine. The flow difference between that range of oil viscosity isn't going to make or break any engine oiling system due to the difference in flow and the "cooling effect" on the engine.

Or Is it an ECU controlled system that's using a feedback loop signal from an oil pressure sensor, and if so how well does it regulate the maximum oil pressure? Is it rock steady at a max pressure? Got any oil pressure vs RPM performance curves of the pressure regulation? If that's the case, and if the oiling system engineers did it right the system should still be designed to run a wide range of oil viscosity.

No oil pump regardless of design or pressure regulation method should be designed to run on the ragged edge of supplying adequate oil flow regardless of what the oil viscosity is. If the pump fails to give adequate lubrication when the oil grade changes a grade or two ... that would be a ridiculously designed oiling system. Just the fact that oil viscosity changes dramatically between a -25F cold start-up to full operating temperature in millions of vehicles in the winter time proves that a properly designed oil pump and oiling system doesn't really care about the KV100 oil viscosity if the correct W rating is used. What does matter the most is: 1) The correct W grade is used for cold start-ups, and 2) The HTHS viscosity is high enough to provide adequate MOFT between moving part to give the most wear protection possible. The oil pump will get enough oil to the parts if the pump is designed right, regardless if the oil is xW-8 or xW-60. Also, like another example mentioned, Ford will spec a 5W-20 to a 5W-50 in the same basic engine depending on use conditions, so obviously the oil pump doesn't care what the KV100 grade is in terms of providing adequate flow, or the cooling effect of the oil viscosity.

 

[siriusc1024]

What are the details on this oil pump pressure regulating system? You used the words "bypass spring opens to hold set pressure", so that sounds like an old fashioned mechanically controlled pressure regulation valve in the oil pump. If that is the case, then oil pumps like that will be in some stage of pressure and volume regulation around 2000 to 3000 RPM, which means the pump is putting out much more oil flow than the oiling system can flow before the pump starts regulating output pressure. They also keep slowly increasing output pressure and flow as RPM increases, meaning they don't quite regulate the output perfectly once in regulation. In a system like that, it really doesn't matter if the oil is a xW-16 to a xW-50 because the pump (if sized correctly) at a relatively low RPM is trying to forcing much more oil through the system than what the minimum flow would be needed to adequately lubricate the engine. The flow difference between that range of oil viscosity isn't going to make or break any engine oiling system due to the difference in flow and the "cooling effect" on the engine.

Or Is it an ECU controlled system that's using a feedback loop signal from an oil pressure sensor, and if so how well does it regulate the maximum oil pressure? Is it rock steady at a max pressure? Got any oil pressure vs RPM performance curves of the pressure regulation? If that's the case, and if the oiling system engineers did it right the system should still be designed to run a wide range of oil viscosity.

No oil pump regardless of design or pressure regulation method should be designed to run on the ragged edge of supplying adequate oil flow regardless of what the oil viscosity is. If the pump fails to give adequate lubrication when the oil grade changes a grade or two ... that would be a ridiculously designed oiling system. Just the fact that oil viscosity changes dramatically between a -25F cold start-up to full operating temperature in millions of vehicles in the winter time proves that a properly designed oil pump and oiling system doesn't really care about the KV100 oil viscosity if the correct W rating is used. What does matter the most is: 1) The correct W grade is used for cold start-ups, and 2) The HTHS viscosity is high enough to provide adequate MOFT between moving part to give the most wear protection possible. The oil pump will get enough oil to the parts if the pump is designed right, regardless if the oil is xW-8 or xW-60. Also, like another example mentioned, Ford will spec a 5W-20 to a 5W-50 in the same basic engine depending on use conditions, so obviously the oil pump doesn't care what the KV100 grade is in terms of providing adequate flow, or the cooling effect of the oil viscosity.

All of that, and all the likes that go with it, is something I can't fathom. Ragged edge of supplying oil. Cooling effect in quotes as if that's not what piston squirters are for.

Try to understand, everyone, without bending things to your version of reality. Focus on the simplicity of this:

At a set pressure a lower viscosity fluid will flow more. It is completely irrelevant to the type of pump or regulation. Any questions on that? I sure hope not.

Now, the updated EA888 engines require 508. They are not the same engine as the previous revisions that spec 504. There are differences in parts, and this information is readily available. The PCM's are tuned differently, as well. Torque comes in at lower RPM. I could describe how lower viscosity oil will lubricate more effectively at lower RPM's than higher viscosity, but what's the point when the crowd can't seem to get past the most basic relationship of pressure and flow.

BTW, 508 is dyed so that dealerships and certified service centers can quickly tell if the correct spec of oil is used. That implies that not only does 504 have the potential to cause damage over the designed life of the engine, but that they expect people who think they know better to ignore the spec. If your engine breaks because you thought it needed 504 instead they won't help you. Running 504 where 508 is specified is operator error.

Don't tell me that 504 is better for an engine spec'd 508. Go ahead and tell the Volkswagen Group.

 

[OilUzer]

@chris719

Based on one of your previous posts, I learned that dexos R is a mod of ACEA C3 or something to that effect.

Does that mean for all practical purposes +/- a little, they are interchangeable if that was the only criterion in selecting an oil?

 

[MParr]

All of that, and all the likes that go with it, is something I can't fathom. Ragged edge of supplying oil. Cooling effect in quotes as if that's not what piston squirters are for.

Try to understand, everyone, without bending things to your version of reality. Focus on the simplicity of this:

At a set pressure a lower viscosity fluid will flow more. It is completely irrelevant to the type of pump or regulation. Any questions on that? I sure hope not.

Now, the updated EA888 engines require 508. They are not the same engine as the previous revisions that spec 504. There are differences in parts, and this information is readily available. The PCM's are tuned differently, as well. Torque comes in at lower RPM. I could describe how lower viscosity oil will lubricate more effectively at lower RPM's than higher viscosity, but what's the point when the crowd can't seem to get past the most basic relationship of pressure and flow.

BTW, 508 is dyed so that dealerships and certified service centers can quickly tell if the correct spec of oil is used. That implies that not only does 504 have the potential to cause damage over the designed life of the engine, but that they expect people who think they know better to ignore the spec. If your engine breaks because you thought it needed 504 instead they won't help you. Running 504 where 508 is specified is operator error.

Don't tell me that 504 is better for an engine spec'd 508. Go ahead and tell the Volkswagen

I would rather run a VW508.00/509.00 oil than any dexos specific 0W20.

 

[siriusc1024]

I would rather run a VW508.00/509.00 oil than any dexos specific 0W20.

Ok, but in a GM engine? In a gasoline TDI GM engine where, as you can see above, they have a specific test for LSPI? That's a failure of logic.

Here's an example of false equivalences. They've been thrown around enough, so my turn.

Mobil ESP 0w-20 is 508. It's also DexosD. Therefore...DexosD is superior to dexos1 Gen 3 because 508 is superior? So, we're going to put in what GM specs for their light diesel engines instead of Mobil 0w-20 Advanced Fuel Economy?

See how that works? It's dumb, but for some reason I keep seeing it. Run the spec.

 

[MParr]

"Ok, but in a GM engine? In a TDI GM engine where, as you can see above, they have a specific test for LSPI? That's a failure of logic."
When you say GM TDI engines, are you talking about the Duramax? The reason I'm asking is TDI is a diesel engine.
European manufacturers have been mass producing TDI engines for a very long time.
LSPI is something that I'm not afraid of. I don't lug my engines, I don't use the Eco Mode, and I run 93 octane gas.

 

[ZeeOSix]

All of that, and all the likes that go with it, is something I can't fathom.

That's because you can't understand it, but others do understand basic Tribology.

Ragged edge of supplying oil. Cooling effect in quotes as if that's not what piston squirters are for.

I wasn't talking only about oil squirters. The oil squirters are sill going to work fine with any KV100 grade from 20 to 50. It does just fine in the Ford Coyote and other engines with oil squirters. You seem to think there's some kind of oil flow shortage if a thicker oil is used. Not enough to matter in terms of lubrication and "cooling effect". People are too hung up on the "cooling effect" of motor oil. The difference between grades is insignificant compared to the other factors that change with a grade change.

Try to understand, everyone, without bending things to your version of reality. Focus on the simplicity of this:

At a set pressure a lower viscosity fluid will flow more. It is completely irrelevant to the type of pump or regulation. Any questions on that? I sure hope not.

But your not factoring in the context of how a PD oil pump actually works on an ICE oiling system. Like I explained in the earlier post, a PD oil pump if designed correctly for the oiling system are over-sized for their application. That's why they start going into pressure relief at a pretty low engine RPM. Once the pump is in pressure relief, the engine doesn't really need any more flow volume than the pump is sending. That goes for any KV100 grade of oil used in an ICE. Remember those "recommended oil viscosity" charts in OMs that showed a whole range of viscosity? Now gone due to CAFE, but still shown in OMs for the same engines in other countries, and also still shown in motorcycle OMs because they aren't victims of CAFE, yet.

Now, the updated EA888 engines require 508. They are not the same engine as the previous revisions that spec 504. There are differences in parts, and this information is readily available. The PCM's are tuned differently, as well. Torque comes in at lower RPM. I could describe how lower viscosity oil will lubricate more effectively at lower RPM's than higher viscosity, but what's the point when the crowd can't seem to get past the most basic relationship of pressure and flow.

Exactly what "differences in parts" is going to require a certain grade of lower KV100 viscosity oil to lubricate them correctly and keep the moving parts separated?

OK, then let's hear how "lower viscosity oil will lubricate more effectively at lower RPM's than higher viscosity, but what's the point when the crowd can't seem to get past the most basic relationship of pressure and flow." How much more lubrication do you think is needed at "lower RPM" when there's already way more than is needed? You have controlled test study data that proves your claim? How many engines have been damaged or have blown-up because "too thick" of oil was used at low RPM? Better not run an engine at "too low" of an RPM after a cold winger start-up because the oil is very thich in that case. Funny how people think engines are so sensitive to oil viscosity, yet millons of them operate from cold start-ups to full operating temperture every day and they survive just fine.

The reality is that using a lower viscosity oil at low RPM with increased engine load will have more potential for increased wear and damage then running a thicker oil. Journal bearings don't like thin oil at low RPM with high rod loads (like getting into the turbo at low RPM situations). In that situation, the MOFT in journal bearing can go to zero and cause metal-to-metal contact and bearing wear. Why do you think every engine used for severe use conditions or track use all specify a higher viscosity? The pump flow it still more than adequate, and the difference in "cooling" doesn't matter to make any real difference. What matters is the HTHS viscosity is adequate for a resulting MOFT between moving parts to minimize wear and damage.

I think the majority of the "crowd" knows the relationship between pressure, flow and how the viscosity is part of that equation. But a lot of people don't quite fully understand the way a PD oil pump works on an ICE oiling system.

BTW, 508 is dyed so that dealerships and certified service centers can quickly tell if the correct spec of oil is used. That implies that not only does 504 have the potential to cause damage over the designed life of the engine, but that they expect people who think they know better to ignore the spec. If your engine breaks because you thought it needed 504 instead they won't help you. Running 504 where 508 is specified is operator error.

Don't tell me that 504 is better for an engine spec'd 508. Go ahead and tell the Volkswagen Group.

So what's the KV100 and HTHS viscosity of those two oils for comparison?

 

[siriusc1024]

"Ok, but in a GM engine? In a TDI GM engine where, as you can see above, they have a specific test for LSPI? That's a failure of logic."
When you say GM TDI engines, are you talking about the Duramax? The reason I'm asking is TDI is a diesel engine.
European manufacturers have been mass producing TDI engines for a very long time.
LSPI is something that I'm not afraid of. I don't lug my engines, I don't use the Eco Mode, and I run 93 octane gas.

Lug the engine? You'd have to be driving something with a manual transmission. Lugging the engine is a factor of LSPI, but what about the vast majority that are automatic transmission vehicles having LSPI issues?

Oil type is another factor. LSPI mitigation is one of the targets of SP oils. GM is investigating further on this specific test. There's probably a reason for that.

The American Petroleum Institute is concerned about LSPI. GM is concerned about LSPI. So is everyone else who makes gas TDI engines. You might not be, but if you stick to the spec you don't have to be. They've got you covered.

I wasn't talking only about oil squirters. The oil squirters are sill going to work fine with any KV100 grade from 20 to 50. It does just fine in the Ford Coyote and other engines with oil squirters. You seem to think there's some kind of oil flow shortage if a thicker oil is used. Not enough to matter in terms of "cooling effect". People are too hung up on the "cooling effect" of motor oil. The difference between grades is insignificant compared to the other factors that change with a grade change.


But your not factoring in the context of how a PD oil pump actually works on an ICE oiling system. Like I explained in the earlier post, a PD oil pump if designed correctly for the oiling system are over-sized for their application. That's why they start going into pressure relief at a pretty low engine RPM. Once the pump is in pressure relief, the engine doesn't really need any more flow volume that the pump is sending. That goes for any KV100 grade of oil used in an ICE.


Exactly what "differences in parts" is going to require a certain grade of oil to lubricate them and keep moving parts separated?

OK, then let's hear how "lower viscosity oil will lubricate more effectively at lower RPM's than higher viscosity, but what's the point when the crowd can't seem to get past the most basic relationship of pressure and flow." How much more lubrication do you need at "lower RPM" when there's already way more than is needed? How many engines have been damaged or have blown-up because "too thick" of oil was used at low RPM? The reality is that using a lower viscosity oil at low RPM with increased engine load will have more potential for increased wear and damage then running a thicker oil. Journal bearings don't like thin oil at low RPM with high rod loads (like getting into the turbo at low RPM). In that situation, the MOFT in journal bearing can go to zero and cause metal-to-metal contact and bearing wear. Why do you think every engine used for severe use conditions or track use all specify a higher viscosity? The pump flow it still more than adequate, and the difference in "cooling" doesn't matter ... what matters is the HTHS viscosity and the resulting MOFT between moving parts.

I think the majority of the "crowed" knows the relationship between pressure, flow and how the viscosity is part of that equation. But a lot of people don't quite fully understand the way a PD oil pump works on an ICE oiling system.


So what's the KV100 and HTHS viscosity of those two oils for comparison?

I'll just focus on this in bold. You're all over the place, but right there is the problem. PD pump. Same volume of oil/cycle. How is pressure developed? Resistance to output flow of the pump. Say setpoint is regulated to 40psi at a particular instance. When 40psi develops, anything more is returned regardless of pump RPM.

A higher viscosity oil has more resistance to flow through the various clearances of components. A lower viscosity has lower resistance. The resultant oil volume travelling through the oil system will be greater for 40psi with lower viscosity oil than higher.

Outside the pressurized oiling system, how is lubrication accomplished? Splash lubrication. Pistons, wrist pins, valves, cam lobes, rockers, cylinder walls, are some. There is no pressurized system forcing oil between components. Lower viscosity oil will ingress more effectively. There is also more oil available to ingress because the lower viscosity oil will be slung around more, in no small part due to the volume of oil being delivered by the pressurized system.

 

[chris719]

@chris719

Based on one of your previous posts, I learned that dexos R is a mod of ACEA C3 or something to that effect.

Does that mean for all practical purposes +/- a little, they are interchangeable if that was the only criterion in selecting an oil?

I'd have to see GMs documentation, but dexos2 oils were all or nearly all ACEA C3 at one point. I picked 12 of them and checked all 12 PDS and they were ACEA C3. Whether that is by definition or just coincidence, that's what was happening. Then, dexos2 became dexosR. Technically dexosR supersedes dexos2 for gasoline engines, so there is no guarantee that a C3 oil will meet dexosR. Outside of the Corvette Z06 and ZR1 etc using the Supercar 5W-50, I would guess that most C3 oils could meet those needs though. Their dexos2 ESP Formula oil got renamed to Supercar and was unchanged otherwise and now carries dexosR.

 

[chris719]

Lug the engine? You'd have to be driving something with a manual transmission. Lugging the engine is a factor of LSPI, but what about the vast majority that are automatic transmission vehicles having LSPI issues?

Clearly you haven't driven a modern car from an American or Japanese marque. GM and others issued software updates to combat LSPI because they were and still are "lugging" engines on purpose for fuel economy reasons.

In fact, I don't know a single person who drives a manual that shifts as soon as any modern automatic transmission in the default drive mode. Even compared to a German car with "sporty" software like BMW and Porsche.

 

[siriusc1024]

Clearly you haven't driven a modern car from an American or Japanese marque.

Clearly I have. There's a 2019 Rogue in the driveway. When you go into eco mode, and it feels like you're lugging the engine, it's really not. It only feels that way. There's a computer between you and the throttle body. If you look into a tune, as I admonished you previously, you'd see there are commanded torque tables and driver demand tables. There are even max torque vs commanded throttle tables. Same tables translate over to shift scheduling on the transmission side. It's impossible to "lug" these engines. Impossible unless you have a manual where you can command all over the RPM range.

 

[chris719]

Clearly I have. There's a 2019 Rogue in the driveway. When you go into eco mode, and it feels like you're lugging the engine, it's really not. It only feels that way. There's a computer between you and the throttle body. If you look into a tune, as I admonished you previously, you'd see there are commanded torque tables and driver demand tables. Same tables translate over to shift scheduling on the transmission side. It's impossible to "lug" these engines. Impossible unless you have a manual where you can command all over the RPM range.

Call it what you will. GM, Ford, Honda, and others were destroying engines with their low RPM torque demands. They all issued firmware to mitigate it for one model or another.

BTW how can we take anyone who willingly purchased a Nissan Rogue seriously when discussing powertrain engineering . I kid, I kid, sorta.

 

[siriusc1024]

Call it what you will. GM, Ford, Honda, and others were destroying engines with their low RPM torque demands. They all issued firmware to mitigate it for one model or another.

BTW how can we take anyone who willingly purchased a Nissan Rogue seriously when discussing powertrain engineering . I kid, I kid, sorta.

It's the woman's. CVT fluid every 3rd oil change.

 

[ZeeOSix]

Lugging the engine is a factor of LSPI. So is oil type. LSPI mitigation is one of the targets of SP oils. GM is going beyond SP on this specific test. There's probably a reason for that.

The American Petroleum Institute is concerned about LSPI. GM is concerned about LSPI. So is everyone else who makes gas TDI engines. You might not be, but if you stick to the spec you don't have to be. They've got you covered.

There's more to lugging at low RPM than just LSPI ... that's what I was focused on, and pointing out that thinner oil is worse off than thicker in that situation. Journal bearings at low RPM lugging conditions have more potential to hurt rod bearings with thinner oil than not. Throw in some LSPI and it's even worse for the bearings, but might not really matter if the piston is smoked first, lol.

I'll just focus on this in bold. You're all over the place, but right there is the problem. PD pump. Same volume of oil. Pressure builds after the pump because there is a resistance to flow. Say setpoint is regulated to 40psi at a particular instance. When 40psi develops, anything more is returned regardless of pump RPM.

You're actually all over the place ... go out of context in the discussion. Clearly don't really understand how a spring loaded pressure relief valved PD pump works on an ICE. The pump output volume isn't constant, it increases pretty much linear with RPM until it starts going into pressure relief. And a spring loaded pressure relief type pump will still keep increasing flow and pressure as the RPM increases because the spring loaded valve just can't regulate to a prefect max pressure. Most pumps will put out 75-90 PSI (some pumps even more) with hot oil at near redline, even though the pump started to go into relief around 2000-2500 RPM. So, the way the PD works, it doesn't really matter if the oil KV100 grade is 20 or 50, or anything in between ... it still provides more than adequate oil volume for proper lubrication.

A higher viscosity oil has more resistance to flow through the various clearances of components. A lower viscosity has lower resistance. The resultant oil volume travelling through the oil system will be greater for 40psi with lower viscosity oil than higher.

It's a small difference when the oil is at full operating temperature, say 200F. Not enough difference to matter. If it mattered, you'd see worn out and blown-up engines all over the place due to lack of lubrication. Especially in the winter when the oil goes from below zero to 200F in millions of vehicles. That doesn't happen if the right W grade is used to start with.

Have you ever ran the calculations to see what the flow difference would be between hot oil that was 3.2 cP (xW-30) vs 2.6 cP {xW-20) through a fixed flow resistance?

Outside the pressurized oiling system, how is lubrication accomplished? Splash lubrication. Pistons, wrist pins, valves, cam lobes, rockers, cylinder walls, are some. There is no pressurized system forcing oil between components. Lower viscosity oil will ingress more effectively. There is also more oil available to ingress because the lower viscosity oil will be slung around more.

Only during the cold start-up to warm-up phase. But again, as long as the correct W grade rating is used there isn't a real problem. If there was, you'd see tons of damaged engines ... but you don't. This is hair splitting. You think when oil is hot and thin that a 20 grade vs a 50 grade is really going to make any difference in lubricating all the non-force fed moving parts. No way, or you'd see the results in millions of engines. It's way more critical in very cold start-ups, and why it's important to have the right W grade in the sump.

The higher volume of oil cools components more effectively.

Not enough to matter ... it's hair splitting. You have study data that shows how much, and how it effects engine wear? If the engine has an oil cooler, and a properly designed cooling system (which pulls heat from the oil too), then it doesn't matter if the oil is a 20 or 50 grade. Even engines like air cooled motorcycle engines still specify thicker oil, like 10W-40 to 20W-50 because it protects better, even though it may run a little hotter oil temps.

Higher viscosity oil also heats up more due to parasitic drag.

True ... but again not enough to really matter. If running thicker oil was so "bad" because it "heated up more" and "didn't cool as much", then why do many high performance engines and engines in track use all use thicker oil. If it was so "detrimental" it wouldn't be used. The plus factor of thicker oil out weighs the minuscule negative factor lf running a bit hotter not cooling as well ... those are minor factors that don't matter in the real world. Ford doesn't spec 5W-50 in some of their V8s for no real good reason. The engineers know a thinner oil will not protect the engine as well during the conditions those engine may be used in.

 

[siriusc1024]

There's more to lugging at low RPM than just LSPI ... that's what I was focused on, and pointing out that thinner oil is worse off than thicker in that situation. Journal bearings at low RPM lugging conditions have more potential to hurt rod bearings with thinner oil than not. Throw in some LSPI and it's even worse for the bearings, but might not really matter if the piston is smoked first, lol.


You're actually all over the place ... go out of context in the discussion. Clearly don't really understand how a spring loaded pressure relief valved PD pump works on an ICE. The pump output volume isn't constant, it increases pretty much linear with RPM until it starts going into pressure relief. And a spring loaded pressure relief type pump will still keep increasing flow and pressure as the RPM increases because the spring loaded valve just can't regulate to a prefect max pressure. Most pumps will put out 75-90 PSI (some pumps even more) with hot oil at near redline, even though the pump started to go into relief around 2000-2500 RPM. So, the way the PD works, it doesn't really matter if the oil KV100 is 20 or 50, or anything in between ... it still provides more than adequate oil volume for proper lubrication.


It's a small difference when the oil is at full operating temperature, say 200F. Not enough diffenence to matter. If it mattered, you'd see worn out and blown-up engines all over the place due to lack of lubrication. Especially in the winter when the oil goes from below zero to 200F in millions of vehicles. That doesn't happen if the right W grade is used to start with.

Have you ever ran the calculations to see what the flow difference would be between hot oil that was 3.2 cP (xW-30) vs 2.6 cP {xW-20) through a fixed flow resitance?


Only during the cold start-up to warm-up phase. But again, as long as the correct W grade rating is used there isn't a real problem. If there was, you'd see tons of damaged engines ... but you don't. This is hair splitting. You think when oil is hot and thin that a 20 grade vs a 50 grade is really going to make any difference in lubricating all the non-force fed moving parts. No way, or you'd see the results in millions of engines. It's way more critical in very cold start-ups, and why it's important to have the right W grade in the sump.


Not enough to matter ... it's hair splitting. You have study data that shows how much, and how it effects engine wear? If the engine has an oil cooler, and a properly designed cooling system (which pulls heat from the oil too), then it doesn't matter if the oil is a 20 or 50 grade. Even engines like air cooled motorcycle engines still specify thicker oil, like 10W-40 to 20W-50 because it protects better, even though it may run a little hotter oil temps.


True ... but again not enough to really matter. If running thicker oil was so "bad" because it "heated up more" and "didn't cool as much", then why do many high performace engines and engines in track use all use thicker oil. If it was so "deterimental" it wouldn't be used. The plus factor of thicker oil out wieghs the minisule negative factor lf running a bit hotter not cooling as well ... those are minor factors that don't matter in the real world. Ford doesn't spec 5W-50 in some of their V8s for no real good reason. The engineers know a thinner oil will not protect the engine as well during the condtions those engine may be used in.

Literally everything you exhausted energy describing is something the manufacturers have tested extensively. They aren't oblivious to what you mentioned.

Stick to the spec.

 

[chris719]

You're actually all over the place ... go out of context in the discussion.

He doesn't understand the Walther equation or ASTM D341 and what happens to oil at it gets hotter. He also doesn't understand that flow out of an orifice nozzle like an oil squirter is not linear with respect to kinematic viscosity. It's not worth wasting time going into detail when he doesn't know the basics and we can easily see every OEM disagrees with him and specifies thicker oils in their more highly loaded applications.