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The smaller tubes add up to more surface area. That is, 1x8 tube can fit nearly 50 1" tubes within it. Much more surface area.
Oil Weight vs Warm Up Time
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Originally Posted By: labman
Why do oil coolers divide the oil up into small tubes? Because it cools better than in a big pan.
Because of a huge surface (=contact) area.
Pfff... you gotta type fast here
Why do oil coolers divide the oil up into small tubes? Because it cools better than in a big pan.
Because of a huge surface (=contact) area.
Pfff... you gotta type fast here
Last edited:
I don't see any thermodynamic reason why two different oils of only slightly different viscosity are going to have enough difference in their ability to "gather heat" from contact with a hot engine to make any statistically relevant difference in warm-up time.
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It depends on what you define as "slightly different".
@ 40C/104F the difference between any two visc fluids (use synths w/170+/- VI) will be 8.5X their difference @ 100C/212F
@ 40C/104F the difference between any two visc fluids (use synths w/170+/- VI) will be 8.5X their difference @ 100C/212F
I'm really curious to an answer for my question.
It would make me feel a little better about running the RTS 5W-40 that I run. Just to know that my cst is dropping closer to operating cst quickly.
Like, if both lines were on a graph, of 5W-40 and 5W-20.. both of them heating up to 100C. It seems like common sense that the downward curve of the 5W-40 would, of course, have a steeper curve than the 5W-20. At the same time, 5W-20, I'm sure, will reach it's operating temperature cst sooner.
But, what I worry is that 5W-40 is staying too thick or something until warm up. But, I'm hoping that, really, since it's thicker, it's heating up faster, getting closer to the low cst that my engine needs.
I drive a 5.0 EFI with 125,000 miles on it. Low mileage in my eyes, but I think it's fine with a 40 weight anyways, it mainly has just be having my curiosity. The sad part is, I can't put my question into proper words. Mainly because of this baby running around..
And btw, do you think RTS 5W-40 is going to be ok for winter in east Tennessee. Let's say the average lows are 10-20F. It should be fine, right? Even if it actually got single digits, it should be ok? I use it because my flat tappet 5.0 EFI is in a truck, and I haul wood, tow vehicles sometimes... just generally work my truck. And when I 4x4, I do raise [censored]. So, I like the idea of extra z/p for the way I use my truck. That's why I use an HDEO, and I use a synthetic version for the 5W-xx rating. And Jaymus isn't my real name... so don't think I'm a stupid hick, lol.
It would make me feel a little better about running the RTS 5W-40 that I run. Just to know that my cst is dropping closer to operating cst quickly.
Like, if both lines were on a graph, of 5W-40 and 5W-20.. both of them heating up to 100C. It seems like common sense that the downward curve of the 5W-40 would, of course, have a steeper curve than the 5W-20. At the same time, 5W-20, I'm sure, will reach it's operating temperature cst sooner.
But, what I worry is that 5W-40 is staying too thick or something until warm up. But, I'm hoping that, really, since it's thicker, it's heating up faster, getting closer to the low cst that my engine needs.
I drive a 5.0 EFI with 125,000 miles on it. Low mileage in my eyes, but I think it's fine with a 40 weight anyways, it mainly has just be having my curiosity. The sad part is, I can't put my question into proper words. Mainly because of this baby running around..
And btw, do you think RTS 5W-40 is going to be ok for winter in east Tennessee. Let's say the average lows are 10-20F. It should be fine, right? Even if it actually got single digits, it should be ok? I use it because my flat tappet 5.0 EFI is in a truck, and I haul wood, tow vehicles sometimes... just generally work my truck. And when I 4x4, I do raise [censored]. So, I like the idea of extra z/p for the way I use my truck. That's why I use an HDEO, and I use a synthetic version for the 5W-xx rating. And Jaymus isn't my real name... so don't think I'm a stupid hick, lol.
Originally Posted By: Gary Allan
It depends on what you define as "slightly different".
@ 40C/104F the difference between any two visc fluids (use synths w/170+/- VI) will be 8.5X their difference @ 100C/212F
I strongly doubt there is going to be much difference (or perhaps any difference) in the heat transfer coefficient of the two oils and THAT is what is ultimately going to decide how quickly (or not) the fluids will pull heat from a hot surface. And since the original poster was asking about warm-up times, THAT is the key to the puzzle.
It depends on what you define as "slightly different".
@ 40C/104F the difference between any two visc fluids (use synths w/170+/- VI) will be 8.5X their difference @ 100C/212F
I strongly doubt there is going to be much difference (or perhaps any difference) in the heat transfer coefficient of the two oils and THAT is what is ultimately going to decide how quickly (or not) the fluids will pull heat from a hot surface. And since the original poster was asking about warm-up times, THAT is the key to the puzzle.
Originally Posted By: Jaymus
Yeah, I'm mainly wondering which oil, in the same car, between a 5W-40 and 5W-20, both starting at 0 degrees F, would hit, say, 150 degrees F first.
That's my main question in the best I can word it.
My guess is that there will be no measurable difference. Your engine is going to produce a fixed amount of heat and making tweaks to your cooling system is likely to have a more relevant effect on how quickly your engine warms up than a minor change in oil viscosity.
It would only cost you the price of one oil change to test this for yourself. Fill with 5W-20 and time how long it takes your cold engine to reach some specific operating temperature while it idles in your driveway. Dump the oil and replace with 5W-40 and repeat the test. Make sure the engine starts out at the same cold temperature both times and that the ambient air temperature is about the same. I'd be shocked if there was more than a low single digit percentage change in the warm-up time. That's likely to be a lot more telling then a bunch of us old pharts throwing around engineering terms and conjecture.
Yeah, I'm mainly wondering which oil, in the same car, between a 5W-40 and 5W-20, both starting at 0 degrees F, would hit, say, 150 degrees F first.
That's my main question in the best I can word it.
My guess is that there will be no measurable difference. Your engine is going to produce a fixed amount of heat and making tweaks to your cooling system is likely to have a more relevant effect on how quickly your engine warms up than a minor change in oil viscosity.
It would only cost you the price of one oil change to test this for yourself. Fill with 5W-20 and time how long it takes your cold engine to reach some specific operating temperature while it idles in your driveway. Dump the oil and replace with 5W-40 and repeat the test. Make sure the engine starts out at the same cold temperature both times and that the ambient air temperature is about the same. I'd be shocked if there was more than a low single digit percentage change in the warm-up time. That's likely to be a lot more telling then a bunch of us old pharts throwing around engineering terms and conjecture.
Perhaps people have been a little loose with their wording and you are mistaking what they mean (at any given temperature, the thinner oil will be closer to "warmed-up" viscosity; thus even if the two oils warm up at the same rate, the thinner one will be closer to operating viscosity) versus what they literally typed. I would think the difference in actual temperature vs. time is going to be very, very small, unless you're in winter conditions where the thicker oil is not being pumped as well.
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Originally Posted By: Familyguy
Originally Posted By: Jaymus
Yeah, I'm mainly wondering which oil, in the same car, between a 5W-40 and 5W-20, both starting at 0 degrees F, would hit, say, 150 degrees F first.
That's my main question in the best I can word it.
My guess is that there will be no measurable difference. Y)
...as I said in my first post ..
Time to temp will be about the same for both.
We then went on holiday excursions.
Originally Posted By: Jaymus
Yeah, I'm mainly wondering which oil, in the same car, between a 5W-40 and 5W-20, both starting at 0 degrees F, would hit, say, 150 degrees F first.
That's my main question in the best I can word it.
My guess is that there will be no measurable difference. Y)
...as I said in my first post ..
Time to temp will be about the same for both.
We then went on holiday excursions.
I am not sure what is taught in universities, but thinner oil runs cooler.
Take a car with an oil tempo gauge and run it at 75 mph on the highway for a good while with thin and thick oils.
There will be a 10 deg F [about] rise in temperature with the thicker oil.
Thick oil heats up more when it is sheared and otherwise manipulated.
It also has a sort of thicker insulating layer on parts. Flow is reduced and that is not good for heat dissipation.
Take a car with an oil tempo gauge and run it at 75 mph on the highway for a good while with thin and thick oils.
There will be a 10 deg F [about] rise in temperature with the thicker oil.
Thick oil heats up more when it is sheared and otherwise manipulated.
It also has a sort of thicker insulating layer on parts. Flow is reduced and that is not good for heat dissipation.
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I tend to agree with that school of thought. The problem with the view is that when you talk viscosity, the conditions are somewhat self correcting. If a heavier oil insulates, it's subjected to more heat, which lowers its viscosity.
When comparing two oils of different grades in terms of warm up, you've got a set of "offsetting penalties" to each that make them ultimately take about the same time to normalized temps.
When comparing two oils of different grades in terms of warm up, you've got a set of "offsetting penalties" to each that make them ultimately take about the same time to normalized temps.
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A weird thing is,when I run M1 15W50,my car`s temp gauge always stays a lil bit lower that any other oil and the engine always feels a bit cooler to the touch,even after long highway runs. Don`t know if it`s in my imagination,but every time I go back to using that oil,the trend happens again. Is it fact or fiction???? Maybe certain engines "like" certain oil? Who knows!
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It will always be a YMMV topic. I think I recall saying that it's a complex and dynamic thing ..and now a few understand what I meant ..or at least why I said it.
I have observed that thicker oil in a differential runs hotter than thinner, all other factors being the same, due to fluid friction. Not by a lot... around 5 and perhaps as much as 10F.
I would theorize the same effects in an engine. FWIW, on a 65 degree day, it takes about 11 miles of steady driving at about 2000 rpm to get the oil temp on my 5.4L Ford from 65F to normal operating temp (190-195F) and that's with a 5W20 synthetic.
I was once told by an engineering source at an OEM mfr. that PAO synthetic gear oils don't transfer heat as well as mineral oils. Not sure if that's true and haven't spent much time tracking it down, but it was an interesting comment.
I would theorize the same effects in an engine. FWIW, on a 65 degree day, it takes about 11 miles of steady driving at about 2000 rpm to get the oil temp on my 5.4L Ford from 65F to normal operating temp (190-195F) and that's with a 5W20 synthetic.
I was once told by an engineering source at an OEM mfr. that PAO synthetic gear oils don't transfer heat as well as mineral oils. Not sure if that's true and haven't spent much time tracking it down, but it was an interesting comment.
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Originally Posted By: Gary Allan
The smaller tubes add up to more surface area. That is, 1x8 tube can fit nearly 50 1" tubes within it. Much more surface area.
No, a bigger tube would have more surface area. The closer the oil is to the wall of the tube, the more it cools. I am amazed that a simple, well know principle of the surface to mass ratio needs to be explained.
The smaller tubes add up to more surface area. That is, 1x8 tube can fit nearly 50 1" tubes within it. Much more surface area.
No, a bigger tube would have more surface area. The closer the oil is to the wall of the tube, the more it cools. I am amazed that a simple, well know principle of the surface to mass ratio needs to be explained.
Hi,
labman - Thanks for your input in this Thread especially your much earlier Post - you and I concur
Speed of flow through ring packs has long been studied in real terms - with similar results - and the same with air cooled car engines (all else being equal). And of course synthetic lubricants have much better flow characteristics as we all know
Thanks labman!
labman - Thanks for your input in this Thread especially your much earlier Post - you and I concur
Speed of flow through ring packs has long been studied in real terms - with similar results - and the same with air cooled car engines (all else being equal). And of course synthetic lubricants have much better flow characteristics as we all know
Thanks labman!
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Originally Posted By: labman
Originally Posted By: Gary Allan
The smaller tubes add up to more surface area. That is, 1x8 tube can fit nearly 50 1" tubes within it. Much more surface area.
No, a bigger tube would have more surface area. The closer the oil is to the wall of the tube, the more it cools. I am amazed that a simple, well know principle of the surface to mass ratio needs to be explained.
Help me out again, labman.
1 8" pipe has roughly 24" of diameter
50 1" pipes have (same cross section, and again roughly) 150" of diameter ..multiply by the same length and tell me which one has more surface area ...one 8" cooling tube or 50 1" cooling tubes.
Gosh!! I didn't think that I needed to explain this simple commonly known 5th grade geometry example (sauce for the goose, pal!!)
That's why a V16 1 liter will never be as economical as a 1 cylinder 1 liter (assuming the same stroke) It's got TREMENDOUS friction in comparison.
It appears that either you didn't read what I posted, or Doug and I don't concur either.
Tell the guys that put 4 valves per cylinder to tell the Egyptians to rethink history.
Originally Posted By: Gary Allan
The smaller tubes add up to more surface area. That is, 1x8 tube can fit nearly 50 1" tubes within it. Much more surface area.
No, a bigger tube would have more surface area. The closer the oil is to the wall of the tube, the more it cools. I am amazed that a simple, well know principle of the surface to mass ratio needs to be explained.
Help me out again, labman.
1 8" pipe has roughly 24" of diameter
50 1" pipes have (same cross section, and again roughly) 150" of diameter ..multiply by the same length and tell me which one has more surface area ...one 8" cooling tube or 50 1" cooling tubes.
Gosh!! I didn't think that I needed to explain this simple commonly known 5th grade geometry example (sauce for the goose, pal!!)
That's why a V16 1 liter will never be as economical as a 1 cylinder 1 liter (assuming the same stroke) It's got TREMENDOUS friction in comparison.
It appears that either you didn't read what I posted, or Doug and I don't concur either.
Tell the guys that put 4 valves per cylinder to tell the Egyptians to rethink history.
Well, what have we concluded?
Will a thicker oil in an engine hit a higher temperature faster than a thinner oil? Or will it practically be equal?
How about when they are both at, say, 50F? Would the thicker oil somewhat warm a noticeable amount faster until they get to, say, the 120F degree range?
I wonder because I use 5W-40 Rotella-T Synthetic, and it would be nice to know it's thinning down somewhat quickly, especially with winter coming on. I hope this will be a good winter oil for my truck, because I want the oil for the extra Zinc/Phosphorous, and I like the 40 weight because I work my truck. I don't want an oil that's too thick for the winter, though. I have an 86 F-150 5.0 EFI flat tappet. I just want what's best for it (That doesn't break the bank, either )
Will a thicker oil in an engine hit a higher temperature faster than a thinner oil? Or will it practically be equal?
How about when they are both at, say, 50F? Would the thicker oil somewhat warm a noticeable amount faster until they get to, say, the 120F degree range?
I wonder because I use 5W-40 Rotella-T Synthetic, and it would be nice to know it's thinning down somewhat quickly, especially with winter coming on. I hope this will be a good winter oil for my truck, because I want the oil for the extra Zinc/Phosphorous, and I like the 40 weight because I work my truck. I don't want an oil that's too thick for the winter, though. I have an 86 F-150 5.0 EFI flat tappet. I just want what's best for it
(That doesn't break the bank, either )Originally Posted By: Jaymus
Well, what have we concluded?
I see where this is headed....
http://www.youtube.com/watch?v=kQFKtI6gn9Y
Well, what have we concluded?
I see where this is headed....
http://www.youtube.com/watch?v=kQFKtI6gn9Y
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