Hypothesis:thicker cold means less warm up wear
- Thread starter Clevy
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Originally Posted By: Clevy
Originally Posted By: Uregina09
Originally Posted By: gregk24
Cold oil is already much thicker than it needs to be.
Thanks for adding nothing.
Ha.
You beat me to it.
I'm looking to establish if a 10w will establish full hydrodynamic lubrication for longer during warm up than a 0w and thereby potentially lessen wear during warm up.
And if that is the case the whole thinner at start up mantra we are being told is wrong.
We are told that thinner at start up lessens wear however we now know that most wear happens during warm up until the additive package activates.
So if the oil can stay thicker til the additive package activates wouldn't that translate to less wear overall.
That is the premise of the thread. If you've got nothing intelligent to add please go pollute someone else's thread.
All oils too thick when cold.
Great answer. Well thought out. Obviously put a lot of time into that one.
Who told us that all oils are too thick when cold? There is a point where the time it takes to reach the sump to the pump starts to cause trouble but other than that extreme cold [lack of oil] the oil will keep the parts separated Heavier may keep the parts separated better as under higher pressure using the cam and lifters/ valvetrain which are the highest loaded parts in an engine.
Originally Posted By: Uregina09
Originally Posted By: gregk24
Cold oil is already much thicker than it needs to be.
Thanks for adding nothing.
Ha.
You beat me to it.
I'm looking to establish if a 10w will establish full hydrodynamic lubrication for longer during warm up than a 0w and thereby potentially lessen wear during warm up.
And if that is the case the whole thinner at start up mantra we are being told is wrong.
We are told that thinner at start up lessens wear however we now know that most wear happens during warm up until the additive package activates.
So if the oil can stay thicker til the additive package activates wouldn't that translate to less wear overall.
That is the premise of the thread. If you've got nothing intelligent to add please go pollute someone else's thread.
All oils too thick when cold.
Great answer. Well thought out. Obviously put a lot of time into that one.
Who told us that all oils are too thick when cold? There is a point where the time it takes to reach the sump to the pump starts to cause trouble but other than that extreme cold [lack of oil] the oil will keep the parts separated Heavier may keep the parts separated better as under higher pressure using the cam and lifters/ valvetrain which are the highest loaded parts in an engine.
I actually believe it does! I always prefer using 10w30/40 over the 0/5 cold viscosities, not just because they cost more and are superflous in my climate, but because this has been disussed a fair while ago and many people believed it to be true unless you live in a very cold climate.
When I check the oil on a cold engine with 10w30 it feels heavy and thick on the dipstick, which should cause a nice thick film in a cold engine. When I check it warm, its like water and I can hardly read it on the stick, and I always thought if oil was that much thinner when the engine is cold then I wouldn't think certain parts would last very long
My personal conclusion, yes I 100% prefer 10w30 over 0/5w30!
When I check the oil on a cold engine with 10w30 it feels heavy and thick on the dipstick, which should cause a nice thick film in a cold engine. When I check it warm, its like water and I can hardly read it on the stick, and I always thought if oil was that much thinner when the engine is cold then I wouldn't think certain parts would last very long
My personal conclusion, yes I 100% prefer 10w30 over 0/5w30!
Originally Posted By: CT8
Who told us that all oils are too thick when cold?
That would be Dr. AE Haas at Motor Oil University.
Who told us that all oils are too thick when cold?
That would be Dr. AE Haas at Motor Oil University.
The general consensus is thick oil when cold flows too slow and
when it finally reaches its destination, doesn't fit in between parts.
when it finally reaches its destination, doesn't fit in between parts.
gathermewool
Site Donor 2025
OP, I gave you my opinion, which seemed to be in context, though you seem to want us to think deeply about a concept for which you can't effectively convey a question aboute. Not only that, but your response seem very smug and cocky. Should someone reply to your OP with, "thanks for adding nothing"? Are you looking for people to simply agree with you and tell you how brilliant your hypothesis is or are you trying to stimulate a dialog?
//
Are we talking about two test engines being started cold and then immediately run under load until warm or two test engines started cold and simply idled until warm, with wear being the only variable of concern?
If the latter, then I'm not sure why you disregarded my post so quickly, since it may be that activation of the add pack on new bearing surfaced and, possibly, the formation of a new anti-wear tribal layer are of little consequence if ANY XW viscosity will provide more than an adequate hydrodynamic wedge.
I'm still not sure why you think a thicker oil than an already thick oil will produce a more consequential wedge. Unless I'm way off base, are engines really running in the interface and boundary layer on a regular basis and relying heavily on an oil's additive package or is the additive package more for lower relative motion contact points, such as wrist pins, cam lobes, etc.?
//
Are we talking about two test engines being started cold and then immediately run under load until warm or two test engines started cold and simply idled until warm, with wear being the only variable of concern?
If the latter, then I'm not sure why you disregarded my post so quickly, since it may be that activation of the add pack on new bearing surfaced and, possibly, the formation of a new anti-wear tribal layer are of little consequence if ANY XW viscosity will provide more than an adequate hydrodynamic wedge.
I'm still not sure why you think a thicker oil than an already thick oil will produce a more consequential wedge. Unless I'm way off base, are engines really running in the interface and boundary layer on a regular basis and relying heavily on an oil's additive package or is the additive package more for lower relative motion contact points, such as wrist pins, cam lobes, etc.?
Clevy,
throw the KV40 and KV100 into the widman operational viscosity calculator, and make the target temperature the sequence IVA temp.
I've no idea on the outcome, and won't be able to play for another 3-4 hours, but it will give an idea what the difference is at the "perfect storm" for warm-up wear.
As Molakule has said, on the way through the warm-up you've still got last run's AW layer, bu the Sequence IVA holds it there for long enough to do measurable damage, not the 200,000+ mile damage that we see in our everyday started cars.
My personal view is not to chase VII, or "W" grades far below what is required, but the difference will be infinitesmal.
throw the KV40 and KV100 into the widman operational viscosity calculator, and make the target temperature the sequence IVA temp.
I've no idea on the outcome, and won't be able to play for another 3-4 hours, but it will give an idea what the difference is at the "perfect storm" for warm-up wear.
As Molakule has said, on the way through the warm-up you've still got last run's AW layer, bu the Sequence IVA holds it there for long enough to do measurable damage, not the 200,000+ mile damage that we see in our everyday started cars.
My personal view is not to chase VII, or "W" grades far below what is required, but the difference will be infinitesmal.
Originally Posted By: gathermewool
Unless I'm way off base, are engines really running in the interface and boundary layer on a regular basis and relying heavily on an oil's additive package or is the additive package more for lower relative motion contact points, such as wrist pins, cam lobes, etc.?
Yes, they are.
Posted elsewhere on BITOG the choosing of new engines for engine test sequences, as they are running lower "stribeck" numbers on more modern engines, into boundary on low speed acceleration.
Unless I'm way off base, are engines really running in the interface and boundary layer on a regular basis and relying heavily on an oil's additive package or is the additive package more for lower relative motion contact points, such as wrist pins, cam lobes, etc.?
Yes, they are.
Posted elsewhere on BITOG the choosing of new engines for engine test sequences, as they are running lower "stribeck" numbers on more modern engines, into boundary on low speed acceleration.
I can play for a while Clevy, as long as you don't mind my
hillbilly logic.
We both grew up on the Canadian prairies watching the northern lights
dance on those long dark winter nights.
The show was worth the misery of standing there at minus whatever.
The next mourning, your dad's car will hardly turn over, but... he pumps
the gas pedal, and she starts, fan belts squealing, everything moaning and groaning.
The tires are square for the first few blocks, the three on the tree
is hard to shift because the gear lube is thick as molasses.
Eventually your parents get a new car. You guys one at a time, turn 16, inherit the
beater and commence to drive the #$@*&%$ out of it until it eventually
blows up or gets bitten by a rabid telephone pole or something.
Years later you take up bracket racing and, like everyone you pour 15W40
or thicker into the engine.
Well ya ain't gonna sit in the pits for 15 minutes with the back-end
jacked up warming up all the fluids, or run the engine in the staging
lanes before every run are you?
In every one of my above examples, the engine oil THANKFULLY was thicker
than it needed to be, and in none of the examples was fuel economy a concern.
hillbilly logic.
We both grew up on the Canadian prairies watching the northern lights
dance on those long dark winter nights.
The show was worth the misery of standing there at minus whatever.
The next mourning, your dad's car will hardly turn over, but... he pumps
the gas pedal, and she starts, fan belts squealing, everything moaning and groaning.
The tires are square for the first few blocks, the three on the tree
is hard to shift because the gear lube is thick as molasses.
Eventually your parents get a new car. You guys one at a time, turn 16, inherit the
beater and commence to drive the #$@*&%$ out of it until it eventually
blows up or gets bitten by a rabid telephone pole or something.
Years later you take up bracket racing and, like everyone you pour 15W40
or thicker into the engine.
Well ya ain't gonna sit in the pits for 15 minutes with the back-end
jacked up warming up all the fluids, or run the engine in the staging
lanes before every run are you?
In every one of my above examples, the engine oil THANKFULLY was thicker
than it needed to be, and in none of the examples was fuel economy a concern.
I've always envisioned anti wear as activating when metal to metal contact occurs creating localized heat. There is no requirement that the oil or engine be at operating temp.
Very viscus oil will not throw off the rod journals well or at all, starving the rings of oil. Its as simple as that.
Very viscus oil will not throw off the rod journals well or at all, starving the rings of oil. Its as simple as that.
Originally Posted By: turtlevette
I've always envisioned anti wear as activating when metal to metal contact occurs creating localized heat. There is no requirement that the oil or engine be at operating temp.
I actually agree with part of that, it's a surface phenomenon, but then the Sequence IVA test has all of the speed and load and contact, but has all of the wear too, by keeping the engine at less than operating temperature.
http://www.swri.org/3pubs/brochure/ae/pdf/SequenceIVA.pdf
There's something going on their.
Member Bobbydavro decribed testing that they have done at lower temperatures (more viscous oil) that gave lower wear, and at higher temperatures (more additive action) which gave lower wear, but these temperatures (in this test engine) gave the worst case of wear, which is why it's used as an accelerated performance test.
Originally Posted By: turtlevette
Very viscus oil will not throw off the rod journals well or at all, starving the rings of oil. Its as simple as that.
So the oil is building up around the big ends and can't get off ?
How long before it empties the sump and creates a ball of taffy around the crank ?
The pistons hold a lot of oil. Even at operating temperatures, the oil is working within the piston and rings for tens of seconds, which is a lifetime in an engine.
The big end will be slinging oil, the oil will be hitting liners, and the rings will be spreading it...
Take out the thermostat, and you will see a lot of cylinder wear in the top ring land area.
With a simply cooled straight 6 (front to back cooling), #1 (coldest) will have more upper cylinder wear, while #6 will have less...same bulk oil temperatures, and same amount of sling off the crank.
I've always envisioned anti wear as activating when metal to metal contact occurs creating localized heat. There is no requirement that the oil or engine be at operating temp.
I actually agree with part of that, it's a surface phenomenon, but then the Sequence IVA test has all of the speed and load and contact, but has all of the wear too, by keeping the engine at less than operating temperature.
http://www.swri.org/3pubs/brochure/ae/pdf/SequenceIVA.pdf
There's something going on their.
Member Bobbydavro decribed testing that they have done at lower temperatures (more viscous oil) that gave lower wear, and at higher temperatures (more additive action) which gave lower wear, but these temperatures (in this test engine) gave the worst case of wear, which is why it's used as an accelerated performance test.
Originally Posted By: turtlevette
Very viscus oil will not throw off the rod journals well or at all, starving the rings of oil. Its as simple as that.
So the oil is building up around the big ends and can't get off ?
How long before it empties the sump and creates a ball of taffy around the crank ?
The pistons hold a lot of oil. Even at operating temperatures, the oil is working within the piston and rings for tens of seconds, which is a lifetime in an engine.
The big end will be slinging oil, the oil will be hitting liners, and the rings will be spreading it...
Take out the thermostat, and you will see a lot of cylinder wear in the top ring land area.
With a simply cooled straight 6 (front to back cooling), #1 (coldest) will have more upper cylinder wear, while #6 will have less...same bulk oil temperatures, and same amount of sling off the crank.
MolaKule
Staff member
Originally Posted By: turtlevette
I've always envisioned anti wear as activating when metal to metal contact occurs creating localized heat. There is no requirement that the oil or engine be at operating temp.
Very viscus oil will not throw off the rod journals well or at all, starving the rings of oil. Its as simple as that.
Actually, the AW additive can activate any time the localized Temperature rises to say 140F or higher, even in absence of metal-to-metal contact.
You can prove this by using the modified PV = kRT equation for liquids.
First, let kR = K, a constant.
Secondly, P (pressure) = Force (load applied)/Area.
Solving for T, T = Force x Volume of oil/(Area x K), and keeping Volume of oil and Area (at say the bearing surface) constant,
so we see that anytime the local Force (load) is increased, the Temperature (T) rises.
I think we can agree that during starting, the loads are minimal and the oil wedge develops due to rotation. Temps are below such that no activation of the high-temp AW chemistry is possible.
As the engine fires to idle rpm, localized loads increase, increasing localized temperatures.
At some point, loads increase further and the localized temperatures rise enough to once again activate a new AW semi-plastic film.
In a 0W40, the mix of oil viscosities is such that the low viscosity base oil component will provide enough cold temp oil film to allow a film wedge to develop sufficiently to provide separation.
In the mid-temperature regime, the higher viscosity component provides sufficient oil film for separation.
As the oil heats up further, the VII molecules uncoil to increase viscosity, thus providing further protection.
If the localized loads increase to reduce the oil film to the point of near asperity contact, the temps increase (as per above), the AW activates to reduce or prevent any metal-to-metal contact.
In other words, one cannot simply generalize a situation without taking into account the step-by-step processes involved.
I've always envisioned anti wear as activating when metal to metal contact occurs creating localized heat. There is no requirement that the oil or engine be at operating temp.
Very viscus oil will not throw off the rod journals well or at all, starving the rings of oil. Its as simple as that.
Actually, the AW additive can activate any time the localized Temperature rises to say 140F or higher, even in absence of metal-to-metal contact.
You can prove this by using the modified PV = kRT equation for liquids.
First, let kR = K, a constant.
Secondly, P (pressure) = Force (load applied)/Area.
Solving for T, T = Force x Volume of oil/(Area x K), and keeping Volume of oil and Area (at say the bearing surface) constant,
so we see that anytime the local Force (load) is increased, the Temperature (T) rises.
I think we can agree that during starting, the loads are minimal and the oil wedge develops due to rotation. Temps are below such that no activation of the high-temp AW chemistry is possible.
As the engine fires to idle rpm, localized loads increase, increasing localized temperatures.
At some point, loads increase further and the localized temperatures rise enough to once again activate a new AW semi-plastic film.
In a 0W40, the mix of oil viscosities is such that the low viscosity base oil component will provide enough cold temp oil film to allow a film wedge to develop sufficiently to provide separation.
In the mid-temperature regime, the higher viscosity component provides sufficient oil film for separation.
As the oil heats up further, the VII molecules uncoil to increase viscosity, thus providing further protection.
If the localized loads increase to reduce the oil film to the point of near asperity contact, the temps increase (as per above), the AW activates to reduce or prevent any metal-to-metal contact.
In other words, one cannot simply generalize a situation without taking into account the step-by-step processes involved.
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Originally Posted By: Shannow
Originally Posted By: turtlevette
Very viscus oil will not throw off the rod journals well or at all, starving the rings of oil. Its as simple as that.
So the oil is building up around the big ends and can't get off ?
How long before it empties the sump and creates a ball of taffy around the crank.
The oil is going to take the easier path thru the lifters. But yes, I take that back, there will be something coming off the journal. Would you agree though the oiling pattern is not optimal.
Originally Posted By: turtlevette
Very viscus oil will not throw off the rod journals well or at all, starving the rings of oil. Its as simple as that.
So the oil is building up around the big ends and can't get off ?
How long before it empties the sump and creates a ball of taffy around the crank.
The oil is going to take the easier path thru the lifters. But yes, I take that back, there will be something coming off the journal. Would you agree though the oiling pattern is not optimal.
Originally Posted By: Clevy
I'm looking to establish if a 10w will establish full hydrodynamic lubrication for longer during warm up than a 0w and thereby potentially lessen wear during warm up.
And if that is the case the whole thinner at start up mantra we are being told is wrong.
We are told that thinner at start up lessens wear however we now know that most wear happens during warm up until the additive package activates.
So if the oil can stay thicker til the additive package activates wouldn't that translate to less wear overall.
That is the premise of the thread. If you've got nothing intelligent to add please go pollute someone else's thread.
All oils too thick when cold.
Great answer. Well thought out. Obviously put a lot of time into that one.
I think it would help, in certain areas, and under a specific RPM range, depending on the design of the engine.
In the main/big end bearings it won't matter, even 3.0 cst oil seems to form an oil wedge thick enough.
But what about the piston/liner assemby and the valvetrain area. at least the piston/liner assembly moves throughall the modes of lubrication, and higher viscosity oil would keep it for a longer part of the cycle in the hydrodynamic/elastohydrodynamic region. Slightly higher rpm would help aswell (without increasing load).
I'm looking to establish if a 10w will establish full hydrodynamic lubrication for longer during warm up than a 0w and thereby potentially lessen wear during warm up.
And if that is the case the whole thinner at start up mantra we are being told is wrong.
We are told that thinner at start up lessens wear however we now know that most wear happens during warm up until the additive package activates.
So if the oil can stay thicker til the additive package activates wouldn't that translate to less wear overall.
That is the premise of the thread. If you've got nothing intelligent to add please go pollute someone else's thread.
All oils too thick when cold.
Great answer. Well thought out. Obviously put a lot of time into that one.
I think it would help, in certain areas, and under a specific RPM range, depending on the design of the engine.
In the main/big end bearings it won't matter, even 3.0 cst oil seems to form an oil wedge thick enough.
But what about the piston/liner assemby and the valvetrain area. at least the piston/liner assembly moves throughall the modes of lubrication, and higher viscosity oil would keep it for a longer part of the cycle in the hydrodynamic/elastohydrodynamic region. Slightly higher rpm would help aswell (without increasing load).
OVERKILL
$100 Site Donor 2021
Originally Posted By: turtlevette
Originally Posted By: Shannow
Originally Posted By: turtlevette
Very viscus oil will not throw off the rod journals well or at all, starving the rings of oil. Its as simple as that.
So the oil is building up around the big ends and can't get off ?
How long before it empties the sump and creates a ball of taffy around the crank.
The oil is going to take the easier path thru the lifters. But yes, I take that back, there will be something coming off the journal. Would you agree though the oiling pattern is not optimal.
Actually, I posted a video of this (and Shannow and I discussed it) regarding thick (non-optimal, an oil being used outside of the range temperature-wise it should probably be used) oil and being tossed out the sides of the rod journal and the "glob" style patterning that presents itself in this scenario versus the "spray" effect you get with warmer oil. It is a real phenomenon, the question is whether it is at all significant in determining the life of the engine
When it is -30C, I'm not concerned about the concept presented in the OP, I'm concerned about THIS. About the lubrication of the cylinder walls, which WILL be suboptimal. Localized heat on things like the valve stems, transferring heat from the combustion chamber up the valve stems will immediately thin any oil that is sitting/rolling on them. This addresses the previously mentioned "penetration" issue (perhaps in the other thread?). However, this does nothing for the heavy oil flying out between the journal and the crank that provides the lubrication of the bores. The pattern is poor, even if the oil immediately thins when it hits the bore surface.
Originally Posted By: Shannow
Originally Posted By: turtlevette
Very viscus oil will not throw off the rod journals well or at all, starving the rings of oil. Its as simple as that.
So the oil is building up around the big ends and can't get off ?
How long before it empties the sump and creates a ball of taffy around the crank.
The oil is going to take the easier path thru the lifters. But yes, I take that back, there will be something coming off the journal. Would you agree though the oiling pattern is not optimal.
Actually, I posted a video of this (and Shannow and I discussed it) regarding thick (non-optimal, an oil being used outside of the range temperature-wise it should probably be used) oil and being tossed out the sides of the rod journal and the "glob" style patterning that presents itself in this scenario versus the "spray" effect you get with warmer oil. It is a real phenomenon, the question is whether it is at all significant in determining the life of the engine
When it is -30C, I'm not concerned about the concept presented in the OP, I'm concerned about THIS. About the lubrication of the cylinder walls, which WILL be suboptimal. Localized heat on things like the valve stems, transferring heat from the combustion chamber up the valve stems will immediately thin any oil that is sitting/rolling on them. This addresses the previously mentioned "penetration" issue (perhaps in the other thread?). However, this does nothing for the heavy oil flying out between the journal and the crank that provides the lubrication of the bores. The pattern is poor, even if the oil immediately thins when it hits the bore surface.
Originally Posted By: used_0il
I can play for a while Clevy, as long as you don't mind my
hillbilly logic.
We both grew up on the Canadian prairies watching the northern lights
dance on those long dark winter nights.
The show was worth the misery of standing there at minus whatever.
The next mourning, your dad's car will hardly turn over, but... he pumps
the gas pedal, and she starts, fan belts squealing, everything moaning and groaning.
The tires are square for the first few blocks, the three on the tree
is hard to shift because the gear lube is thick as molasses.
Eventually your parents get a new car. You guys one at a time, turn 16, inherit the
beater and commence to drive the #$@*&%$ out of it until it eventually
blows up or gets bitten by a rabid telephone pole or something.
Years later you take up bracket racing and, like everyone you pour 15W40
or thicker into the engine.
Well ya ain't gonna sit in the pits for 15 minutes with the back-end
jacked up warming up all the fluids, or run the engine in the staging
lanes before every run are you?
In every one of my above examples, the engine oil THANKFULLY was thicker
than it needed to be, and in none of the examples was fuel economy a concern.
Ha.
Took a page right out of my life,except I bought my first car. My parents wouldn't let me touch their vehicles.
Hillbilly logic
Love it.
Alright. So even though the bearings would be ok running a thicker cold viscosity I see that those globs will not lubricate the rings or cylinder walls well whatsoever.
Gathermewool. I did t dismiss your post,it's just you mentioned a coupe points that I needed to look into before commenting further on them.
Thanks for everyone's input.
I saw a used oil analysis where the owner used a 5w-40 in 2 intervals and lead increased 3 fold,but a 15w40 had low lead levels.
Not that I put much stock in a used oil analysis in regards to wear however based on the trends it seems lead wear increased significantly using an oil with a lower cold value.
I just found it interesting.
I can play for a while Clevy, as long as you don't mind my
hillbilly logic.
We both grew up on the Canadian prairies watching the northern lights
dance on those long dark winter nights.
The show was worth the misery of standing there at minus whatever.
The next mourning, your dad's car will hardly turn over, but... he pumps
the gas pedal, and she starts, fan belts squealing, everything moaning and groaning.
The tires are square for the first few blocks, the three on the tree
is hard to shift because the gear lube is thick as molasses.
Eventually your parents get a new car. You guys one at a time, turn 16, inherit the
beater and commence to drive the #$@*&%$ out of it until it eventually
blows up or gets bitten by a rabid telephone pole or something.
Years later you take up bracket racing and, like everyone you pour 15W40
or thicker into the engine.
Well ya ain't gonna sit in the pits for 15 minutes with the back-end
jacked up warming up all the fluids, or run the engine in the staging
lanes before every run are you?
In every one of my above examples, the engine oil THANKFULLY was thicker
than it needed to be, and in none of the examples was fuel economy a concern.
Ha.
Took a page right out of my life,except I bought my first car. My parents wouldn't let me touch their vehicles.
Hillbilly logic
Love it.
Alright. So even though the bearings would be ok running a thicker cold viscosity I see that those globs will not lubricate the rings or cylinder walls well whatsoever.
Gathermewool. I did t dismiss your post,it's just you mentioned a coupe points that I needed to look into before commenting further on them.
Thanks for everyone's input.
I saw a used oil analysis where the owner used a 5w-40 in 2 intervals and lead increased 3 fold,but a 15w40 had low lead levels.
Not that I put much stock in a used oil analysis in regards to wear however based on the trends it seems lead wear increased significantly using an oil with a lower cold value.
I just found it interesting.
MolaKule
Staff member
Oil sling (splash lubrication) has done a good job for over a hunnerd years.
I think many if not most modern engines also have oil squirters which not only cool the underside of the piston crown and the backside of the rings, but also provide quite an ample supply of oil splash to the cylinder walls.
In addition to splash lubrication from oil sling and squirters, there is, according to high speed crankcase photography, quite a bit of lubricant "mist" in the lower end which also contributes to cylinder wall lubrication.
A mist implies a hot, thin oil.
So as for me, give me the lowest viscosity oil commensurate with at least a 1.5 um hydrodynamic film AND with proper AW additives when I want to put my "foot" into it.
I think many if not most modern engines also have oil squirters which not only cool the underside of the piston crown and the backside of the rings, but also provide quite an ample supply of oil splash to the cylinder walls.
In addition to splash lubrication from oil sling and squirters, there is, according to high speed crankcase photography, quite a bit of lubricant "mist" in the lower end which also contributes to cylinder wall lubrication.
A mist implies a hot, thin oil.
So as for me, give me the lowest viscosity oil commensurate with at least a 1.5 um hydrodynamic film AND with proper AW additives when I want to put my "foot" into it.
Last edited:
MolaKule
Staff member
Originally Posted By: Clevy
...I saw a used oil analysis where the owner used a 5w-40 in 2 intervals and lead increased 3 fold,but a 15w40 had low lead levels.
Not that I put much stock in a used oil analysis in regards to wear however based on the trends it seems lead wear increased significantly using an oil with a lower cold value.
I just found it interesting.
Then Why are you using that example to try and make a case that thicker is better?
We're currently working on 8 cSt oils with advanced additive packages and see both less friction AND wear as compared to 0W20s in two identical blueprinted 4 cyl engines.
The earlier the oil gets to the sliding and rubbing components, the sooner films form, the sooner additives get into place, and the sooner cooling takes place.
...I saw a used oil analysis where the owner used a 5w-40 in 2 intervals and lead increased 3 fold,but a 15w40 had low lead levels.
Not that I put much stock in a used oil analysis in regards to wear however based on the trends it seems lead wear increased significantly using an oil with a lower cold value.
I just found it interesting.
Then Why are you using that example to try and make a case that thicker is better?
We're currently working on 8 cSt oils with advanced additive packages and see both less friction AND wear as compared to 0W20s in two identical blueprinted 4 cyl engines.
The earlier the oil gets to the sliding and rubbing components, the sooner films form, the sooner additives get into place, and the sooner cooling takes place.
Last edited:
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