Cold Oil Questions...
- Thread starter dblshock
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another thought is that the full lubrication system is just not possible stone cold but that's ok for a breif period of warm-up time.
sorry for my stumbling around but that BMW 10/60 was not going to be splashed or squirted anytime soon at 6F.
sorry for my stumbling around but that BMW 10/60 was not going to be splashed or squirted anytime soon at 6F.
Originally Posted By: blupupher
Well said. The cold pour is a part of the picture, but not all of it. The straw in jello is a great analogy.
Also you have to remember that the oil still has to drain back down to the pan once pumped, so the oil pump may be able to suck the pan dry if the oil does not drain back down on it's own fast enough, which is exactly what the cold pour tests show.
None of the SAE literature that I've seen EVER mentions this as a failure mechanism, although there is some BITOG lore that keeps describing it.
The MRV is the measure of whether the oil can make it to the oil pump through the pick-up...two mechanisms of failure are the aforementioned pulling a hole in the oil that then doesn't refill, and the other is that the column of oil separates in the suction line (basically pulled apart due to too high viscosity)...those are the the conditions that the standardised tests are trying to prevent.
IF the phenomenon of insufficient drainback velocity was an actual issue, then there's be a test for it...again, I've not seen the SAE reference it, but would be happily convinced if someone showed me an actual failure (other than one that somebody saw allegedly on a racetrack due to "massively thick" oil, but can't even name the vehicle make).
Once it's made it to the pump, the gel structure if it exists is largely broken, and the oil has been through some level of heating due to the shearing between working surfaces...I really doubt that it's going to struggle getting back.
Well said. The cold pour is a part of the picture, but not all of it. The straw in jello is a great analogy.
Also you have to remember that the oil still has to drain back down to the pan once pumped, so the oil pump may be able to suck the pan dry if the oil does not drain back down on it's own fast enough, which is exactly what the cold pour tests show.
None of the SAE literature that I've seen EVER mentions this as a failure mechanism, although there is some BITOG lore that keeps describing it.
The MRV is the measure of whether the oil can make it to the oil pump through the pick-up...two mechanisms of failure are the aforementioned pulling a hole in the oil that then doesn't refill, and the other is that the column of oil separates in the suction line (basically pulled apart due to too high viscosity)...those are the the conditions that the standardised tests are trying to prevent.
IF the phenomenon of insufficient drainback velocity was an actual issue, then there's be a test for it...again, I've not seen the SAE reference it, but would be happily convinced if someone showed me an actual failure (other than one that somebody saw allegedly on a racetrack due to "massively thick" oil, but can't even name the vehicle make).
Once it's made it to the pump, the gel structure if it exists is largely broken, and the oil has been through some level of heating due to the shearing between working surfaces...I really doubt that it's going to struggle getting back.
I did an UOA a long long time ago when I still had my E92 M3. I ran the Castrol 10W60 that BMW recommended for that car during summer/winter after speaking with their master tech. The UOA showed that the oil sheared down considerably after driving the car a thousand miles or so (did a track day and so did an early OCI). Ended up being more of a 40 grade. In the cold, you're really just worrying about the 10W but again, when I sold the M3, there were no wear/compression/oil burning issues.
Originally Posted By: Tom NJ
These kind of cold pour tests are measuring the oil's ability to flow under its own weight....
That's a very nice explanation, Tom. There's a very good reason we don't rely solely on pour point up here, or at least it's a very good idea not to.
These kind of cold pour tests are measuring the oil's ability to flow under its own weight....
That's a very nice explanation, Tom. There's a very good reason we don't rely solely on pour point up here, or at least it's a very good idea not to.
A little off topic, but wanted to comments on some stuff this guy says in the video. After all the discussions about hydrodynamic journal bearings, and bearing minimum oil film thickness vs viscosity, etc ... the guy makes a statement (at t=8:30) that's not true about low oil pressure causing bearing failure in this use case. Low oil pressure could be said to have "caused" the failure only in the indirect sense that abnormally low oil pressure on the track indicates the oil has really thinned down.
What makes the bearing fail is loss of proper oil film thickness due to the viscosity getting too low from increased heat - regardless if the the oil pressure is normal or low. Lower oil pressure due to hotter oil (with PD pump) doesn't mean there is a lack of flow, it's just an indication of less flow resistance due to the hotter/thinner oil. The same volume of oil is being pumped (less any slight increased pump slippage due to thinner oil) ... it just takes less pressure to push that same positive volume output through the oiling system.
https://youtu.be/ASAdkJydBFU?t=8m30s
I guess you could say that if you're running a car real hard for long periods on the track, and the oil pressure gets extremely low (compared to what it is with normal street driving), that's an indication the oil is becoming very thin due to heat, and it's an early warning sign that you're probably close to loosing a safe oil film thickness in the bearings.
Yet at t=7:33 he talks about using 0W-20 in a 4 hr track session and getting the oil to 270 F. Then doing a UOA at 4000 miles, and the oil was just fine and didn't show any signs of wear metals. So I guess he concluded the bearings survived just fine on 0W-20 at 270 F in that particular track session. Could be, but wonder how close he was to chewing up some bearings ... ?
https://youtu.be/ASAdkJydBFU?t=7m33s
What makes the bearing fail is loss of proper oil film thickness due to the viscosity getting too low from increased heat - regardless if the the oil pressure is normal or low. Lower oil pressure due to hotter oil (with PD pump) doesn't mean there is a lack of flow, it's just an indication of less flow resistance due to the hotter/thinner oil. The same volume of oil is being pumped (less any slight increased pump slippage due to thinner oil) ... it just takes less pressure to push that same positive volume output through the oiling system.
https://youtu.be/ASAdkJydBFU?t=8m30s
I guess you could say that if you're running a car real hard for long periods on the track, and the oil pressure gets extremely low (compared to what it is with normal street driving), that's an indication the oil is becoming very thin due to heat, and it's an early warning sign that you're probably close to loosing a safe oil film thickness in the bearings.
Yet at t=7:33 he talks about using 0W-20 in a 4 hr track session and getting the oil to 270 F. Then doing a UOA at 4000 miles, and the oil was just fine and didn't show any signs of wear metals. So I guess he concluded the bearings survived just fine on 0W-20 at 270 F in that particular track session. Could be, but wonder how close he was to chewing up some bearings ... ?
https://youtu.be/ASAdkJydBFU?t=7m33s
Originally Posted By: dblshock
I often see these vids depict heavy oil poured out like a molasses while cold, but engines don't pour oil they pump it and pressurize it, so I wonder how and if that changes this characterization?
Let's not forget that the oil has to reach the oil pump . Then think what happens to the oil when it is in the pump.Think of sucking a thick milk shake vs. milk through a straw.
I often see these vids depict heavy oil poured out like a molasses while cold, but engines don't pour oil they pump it and pressurize it, so I wonder how and if that changes this characterization?
Let's not forget that the oil has to reach the oil pump . Then think what happens to the oil when it is in the pump.Think of sucking a thick milk shake vs. milk through a straw.
Originally Posted By: ZeeOSix
A little off topic, but wanted to comments on some stuff this guy says in the video. After all the discussions about hydrodynamic journal bearings, and bearing minimum oil film thickness vs viscosity, etc ... the guy makes a statement (at t=8:30) that's not true about low oil pressure causing bearing failure in this use case. Low oil pressure could be said to have "caused" the failure only in the indirect sense that abnormally low oil pressure on the track indicates the oil has really thinned down.
What makes the bearing fail is loss of proper oil film thickness due to the viscosity getting too low from increased heat - regardless if the the oil pressure is normal or low. Lower oil pressure due to hotter oil (with PD pump) doesn't mean there is a lack of flow, it's just an indication of less flow resistance due to the hotter/thinner oil. The same volume of oil is being pumped (less any slight increased pump slippage due to thinner oil) ... it just takes less pressure to push that same positive volume output through the oiling system.
https://youtu.be/ASAdkJydBFU?t=8m30s
I guess you could say that if you're running a car real hard for long periods on the track, and the oil pressure gets extremely low (compared to what it is with normal street driving), that's an indication the oil is becoming very thin due to heat, and it's an early warning sign that you're probably close to loosing a safe oil film thickness in the bearings.
Yet at t=7:33 he talks about using 0W-20 in a 4 hr track session and getting the oil to 270 F. Then doing a UOA at 4000 miles, and the oil was just fine and didn't show any signs of wear metals. So I guess he concluded the bearings survived just fine on 0W-20 at 270 F in that particular track session. Could be, but wonder how close he was to chewing up some bearings ... ?
https://youtu.be/ASAdkJydBFU?t=7m33s
I agree and I think he makes a few good points, but again starts to interject his "experience" on top of facts. Lets be honest, most of what we "know" is based on experience (first/second hand). Besides auto/oil industry, we don't have the appropriate data or tests to really determine "best".
His biggest take away, IMHO, is today's oils are pretty good and it really doesn't matter at the end of the day.
A little off topic, but wanted to comments on some stuff this guy says in the video. After all the discussions about hydrodynamic journal bearings, and bearing minimum oil film thickness vs viscosity, etc ... the guy makes a statement (at t=8:30) that's not true about low oil pressure causing bearing failure in this use case. Low oil pressure could be said to have "caused" the failure only in the indirect sense that abnormally low oil pressure on the track indicates the oil has really thinned down.
What makes the bearing fail is loss of proper oil film thickness due to the viscosity getting too low from increased heat - regardless if the the oil pressure is normal or low. Lower oil pressure due to hotter oil (with PD pump) doesn't mean there is a lack of flow, it's just an indication of less flow resistance due to the hotter/thinner oil. The same volume of oil is being pumped (less any slight increased pump slippage due to thinner oil) ... it just takes less pressure to push that same positive volume output through the oiling system.
https://youtu.be/ASAdkJydBFU?t=8m30s
I guess you could say that if you're running a car real hard for long periods on the track, and the oil pressure gets extremely low (compared to what it is with normal street driving), that's an indication the oil is becoming very thin due to heat, and it's an early warning sign that you're probably close to loosing a safe oil film thickness in the bearings.
Yet at t=7:33 he talks about using 0W-20 in a 4 hr track session and getting the oil to 270 F. Then doing a UOA at 4000 miles, and the oil was just fine and didn't show any signs of wear metals. So I guess he concluded the bearings survived just fine on 0W-20 at 270 F in that particular track session. Could be, but wonder how close he was to chewing up some bearings ... ?
https://youtu.be/ASAdkJydBFU?t=7m33s
I agree and I think he makes a few good points, but again starts to interject his "experience" on top of facts. Lets be honest, most of what we "know" is based on experience (first/second hand). Besides auto/oil industry, we don't have the appropriate data or tests to really determine "best".
His biggest take away, IMHO, is today's oils are pretty good and it really doesn't matter at the end of the day.
Which is MRV, and not pour point on its own.
Numerous M3 V8 UOAs have shown drastic decrease in lead/copper aka bearing wear when switch from 10W60 to 0W40, and I'm sure a lot of them ran their car in climate higher than 6F.
But is this info relevant? I don't think so since most cars on BITOG just don't run 10W60 from the factory anyway.
But is this info relevant? I don't think so since most cars on BITOG just don't run 10W60 from the factory anyway.
Originally Posted By: ZeeOSix
What makes the bearing fail is loss of proper oil film thickness due to the viscosity getting too low from increased heat - regardless if the the oil pressure is normal or low. Lower oil pressure due to hotter oil (with PD pump) doesn't mean there is a lack of flow, it's just an indication of less flow resistance due to the hotter/thinner oil. The same volume of oil is being pumped (less any slight increased pump slippage due to thinner oil) ... it just takes less pressure to push that same positive volume output through the oiling system.
https://youtu.be/ASAdkJydBFU?t=8m30s
I guess you could say that if you're running a car real hard for long periods on the track, and the oil pressure gets extremely low (compared to what it is with normal street driving), that's an indication the oil is becoming very thin due to heat, and it's an early warning sign that you're probably close to loosing a safe oil film thickness in the bearings.
Yet at t=7:33 he talks about using 0W-20 in a 4 hr track session and getting the oil to 270 F. Then doing a UOA at 4000 miles, and the oil was just fine and didn't show any signs of wear metals. So I guess he concluded the bearings survived just fine on 0W-20 at 270 F in that particular track session. Could be, but wonder how close he was to chewing up some bearings ... ?
https://youtu.be/ASAdkJydBFU?t=7m33s
.....I agree....
That's the key point in the "thick/thin" issue, in that when you are in hydrodynamic lubrication (and bearings should be), it doesn't matter how thick the oil film is, the protection is there...nothing touches.
Redline 0w20 has an HTHS of 2.9 which should also be considered. It's the same as an ILSAC 30....TGMO at 2.6, and one of them (there are multiple), CATERHAM tested dropped to 2.4 inside a few hundred miles may well have had a different outcome.
The thinner stuff has lower "headroom", safety margin, whatever...and even with UOA, you won't know exactly how much margin that you have, until you don't.
May well be fine, until you pick up some leaves or a bag, and you need that safety margin.
What makes the bearing fail is loss of proper oil film thickness due to the viscosity getting too low from increased heat - regardless if the the oil pressure is normal or low. Lower oil pressure due to hotter oil (with PD pump) doesn't mean there is a lack of flow, it's just an indication of less flow resistance due to the hotter/thinner oil. The same volume of oil is being pumped (less any slight increased pump slippage due to thinner oil) ... it just takes less pressure to push that same positive volume output through the oiling system.
https://youtu.be/ASAdkJydBFU?t=8m30s
I guess you could say that if you're running a car real hard for long periods on the track, and the oil pressure gets extremely low (compared to what it is with normal street driving), that's an indication the oil is becoming very thin due to heat, and it's an early warning sign that you're probably close to loosing a safe oil film thickness in the bearings.
Yet at t=7:33 he talks about using 0W-20 in a 4 hr track session and getting the oil to 270 F. Then doing a UOA at 4000 miles, and the oil was just fine and didn't show any signs of wear metals. So I guess he concluded the bearings survived just fine on 0W-20 at 270 F in that particular track session. Could be, but wonder how close he was to chewing up some bearings ... ?
https://youtu.be/ASAdkJydBFU?t=7m33s
.....I agree....
That's the key point in the "thick/thin" issue, in that when you are in hydrodynamic lubrication (and bearings should be), it doesn't matter how thick the oil film is, the protection is there...nothing touches.
Redline 0w20 has an HTHS of 2.9 which should also be considered. It's the same as an ILSAC 30....TGMO at 2.6, and one of them (there are multiple), CATERHAM tested dropped to 2.4 inside a few hundred miles may well have had a different outcome.
The thinner stuff has lower "headroom", safety margin, whatever...and even with UOA, you won't know exactly how much margin that you have, until you don't.
May well be fine, until you pick up some leaves or a bag, and you need that safety margin.
Originally Posted By: 1JZ_E46
Originally Posted By: Ohle_Manezzini
He poured a 10w60 at 6F? Who use a track car at 6F without a preheat? Non sense.
It's not a track car. It's a street car, that happens to do pretty well at the track. I know 15+ people here in the PNW that daily an E46 or E92 M3. All use 10W-60.
Its a track car when you hit the track, when you need the 10w60.
Its getting down to 6F ? Just preheat the [censored] thing.
Originally Posted By: Ohle_Manezzini
He poured a 10w60 at 6F? Who use a track car at 6F without a preheat? Non sense.
It's not a track car. It's a street car, that happens to do pretty well at the track. I know 15+ people here in the PNW that daily an E46 or E92 M3. All use 10W-60.
Its a track car when you hit the track, when you need the 10w60.
Its getting down to 6F ? Just preheat the [censored] thing.
Last edited:
Couple of good videos showing effect of cold weather on different grades of oil. Part 1 and Part 2.
Part 1
https://www.youtube.com/watch?v=OWiQyR7PWII
Part 2
https://www.youtube.com/watch?v=ETKECO86VS4
Part 1
https://www.youtube.com/watch?v=OWiQyR7PWII
Part 2
https://www.youtube.com/watch?v=ETKECO86VS4
great video. Thanks
If I lived in WI, I'd think about stuff like this. Oil gellation would be a concern.
Out here, we have new AR laws to think about and oil is just there. Anything up to straight SAE 30 will work as long as you don't live in Tahoe/Truckee or Susanville (might as well be WI ...)
But, the problem with these tests is how the oil was cooled. Do it wrong and you will gellate the oil. And that is maybe not happening in your motor...
Up there with your winters, just run 0W-XX and be happy. Or, if garage kept, maybe 5W-XX ...
Just don't think too hard about all those millions and millions of vehicles that ran into the sunset on 30 oil for about the last 75 out of a 100 years. Especially the ones with 6-volt systems. According to modern thinking, they should have been locked solid all winter and could not be started, anywhere, anytime ...
Out here, we have new AR laws to think about and oil is just there. Anything up to straight SAE 30 will work as long as you don't live in Tahoe/Truckee or Susanville (might as well be WI ...)
But, the problem with these tests is how the oil was cooled. Do it wrong and you will gellate the oil. And that is maybe not happening in your motor...
Up there with your winters, just run 0W-XX and be happy. Or, if garage kept, maybe 5W-XX ...
Just don't think too hard about all those millions and millions of vehicles that ran into the sunset on 30 oil for about the last 75 out of a 100 years. Especially the ones with 6-volt systems. According to modern thinking, they should have been locked solid all winter and could not be started, anywhere, anytime ...
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