I did read the thread. I saw multiple references to Rotella T (conventional) 15w40, which is too heavy for anything but a worn-out beater gasoline engine or an air-cooled gasoline engine. Which is why I SPECIFICALLY mentioned the synthetic 5w40 version, which gets down much closer to the 0w40 that the OP asked about. IMO, Rotella synthetic 5w40 will provide all the cold flow he's looking for, but the high VI of the synthetic Rotella base oil will also protect an engine like a Cad 500 just fine in Death Valley heat if necessary.
I am talking about water cooled engines. It's in the book. normal summer temperature ranges around here call for either xW40 or xW50 based on the chart in the owner's manual. xW30 is for winter only.
The guy has a 70 Eldorado. Not sure how many times this car has seen 5K, or this engine. I suspect more than once. I have a new Honda CR-V and use Castrol Edge. Never used anything but synthetic oil since I got it. The engine will never see anything else. All conventional oils DO leave some varnish. Now Pennsylvania oils leave SLUDGE. I'd only use a Pennsylvania oil in a Russian car that I HATED. Like a LADA (Fiat) or a Muscovitch. Doesn't make any difference what you use in those damn things.
Not from ME. Rotella OIL straight weights were made for SEVERE engine use. (Trucks etc) and are great on cars with high revving engines. I have my own opinions of what weight to use. Depending on climate. In Wisconsin where I grew up 10 weight in winter and 30 weight in summer. I don't really believe in multi-weight oil. We could get into a hot debate on that. I used to work for Texaco and had fun arguing with the refinery engineers and making them agree with me that THERE IS REALLY NO SUCH THING. You see, all you do with multi-weight oils is change the clock. The amount of time it takes to change the viscosity from what it is at the ambient temperature to run hot. The oil is still the same - ALL fluids change when heated and cooled. You can't escape that, just fudge with how long it takes to get from point A to Point B.
Suffice it to say, you're reguritating myths and legends that are 30 years old. Today's "dino" oils are highly refined. Even the most basic Group II base stocks are so refined that it really doesn't matter where the original crude came from, the waxes and other contaminants are long since removed before it gets put in a bottle and sold as motor oil. Group III+ oils are synthetics derived from petroleum that has gone through multiple refining steps that basically dismantle the molecules and put them back together in a very consistent way. Group IV synthetics are synthesized from natural gas. The idea that there is something different about "Pennsylvania" motor oil is just a myth, Pennzoil and Quaker State may have been pretty crappy oils back in the 70s, but today both of them (even the low-end lines, not just Q or Pennzoil Platinum) consistently yield some of the best used oil analysis results reported.
Quaker State and Pennzoil are paraffin based. Other oil companies are asphalt based. Pennsylvania oil is not the idea for today's engines. Which is why both companies are now heavy into synthetics. Have you see Castrol's latest data on testing oils? Edge versus everything else?
Its obvious that you don't really understand what a "multi weight" oil means. "The time it takes to change viscosity" doesn't even come into play at all. All measurements are made with the fluid fully cold or fully hot.
Yes, all oils change thickness with temperature. But grossly oversimplyfing- the AMOUNT (not the speed) that a fluids thickness changes with temperature varies a huge amount from fluid to fluid. The way that you qualify a fluid to be a "multi weight" oil is to have a very high viscosity index- meaning that the viscosity change with temperature is low. A low viscosity index means that thickness changes greatly with temperature. So whereas a "straight 30 weight" oil may be as thick as honey at 0 degrees F and as thin as water at 212 F, a 5w40 will be as thick as room-temperature maple syrup at 0F and as thin as lukewarm syrup at 212F. IOW it doesn't change thickness NEARLY as much, even after its fully heated or fully cooled and allowed to come to equilibrium.
Example time: How much does the thickness of honey change when you take it from 40 degrees F to 180 degrees F? A lot. Honey has a low viscosity index over that temperature change. Now, how much does the thickness of water change when you take it from 40 degrees F to 180 degrees F? Hardly at all, in fact not enough to measure without sensitive instruments. Water has a high VI over that temperature range. You want your engine oil to behave more like water (although it needs to be thicker) than you want it to behave like honey.
Making an oil have a high VI used to be done primarily with viscosity modifiers- long-chain polymers that coil up tightly at low temperatures letting the fluid flow easily, then uncoil and "tangle" at high temperatures to thicken the fluid. VI modifiers are used far less these days since base stock oils are now made with much higher inherent VI. This is another good reason to use a synthetic in any engine- Rotella T Synthetic for example is made using Shell's XHVI base fluid (a group III+ hydroprocessed slack wax derivative) which has a viscosity index much higher than most conventional oils, and in fact higher than many Group IV PAO base oils. This means that it can flow easily when cold and stay thick when hot WITHOUT adding the long coily polymers, which themselves do not lubricate and in fact contribute to deposit formation when they break down. This USED to be a good argument for sticking with a single-grade oil. No more.
These characteristics (high VI base oil, combined with less need for VI improving polymers) are a good reason to consider a synthetic or semi-synthetic for any vehicle regardless of age- ESPECIALLY given the OP's desire for an oil that both flows in cold and protects in heat.
Pennzoil "yellow bottle" is not synthetic, yet it consistently yields superb oil analysis results. I used to be a Pennzoil hater too, but the facts today say its among the best conventional oils out there. Welcome to this century, quit living in the previous one.
I could care less about any oil company's self-test results. What impresses me more is that Castrol Edge does well on independent tests too. Edge, Pennzoil Platinum, Mobil 1, Valvoline SynPower, etc. are all very comparable.
Sure I do. It deflies the LAW of fluids. Look - ther FACT is that at any given temperature the fluid is constant as far as thickness and lubrication potential is. It gets thicker when it is cold and thinner when it is hot. ALL fluids behave that way. All that molecule chaining does is to change the curve of the change. It modifies time. In other words it stays thicker longer at higher temperatures.
ALL fluids get thicker when they are cold and thinner when they are HOT. That includes motor oil. What you do when you screw with the chemistry is you change the RATE of change over time.In simple terms a multi-weight oil takes longer to get thin when the engine gets hot, but thin it gets. The FACT is also that when you deal with a "straight weight" oil - say 30W - technically it doesn't STAY 30 weight, it THINGS out. But it stays thicker than a 20 weight. Thinner than a 50 weight. a 10 W. 30 oil supposedly acts like a 10 weight when hot and a 30 weight when cold. In reality it doesn't act all that much differently than a 20 weight.
Well those that aren't synthetics. That's what both companies packaging says.
Actually not. SHell Rotella and Taxaco Havoline are considerably better.
I was speaking to the independent tests.. It performs much better than the other synthetics. Remember,"Edge" is not Castrol's only synthetic, nor is Mobil One Mobil's only synthetic. Head to head, Edge is the best.
Look at the viscosity curve. It doesn't have time on any scale. Yes, many people measure viscosity as a rate of flow through a fixed size hole, but that doesn't mean there's a T in the definition.
No, not all fluids do this. Some fluids aren't even Newtonian at all.
I had this argument with a refinery engineer almost 30 years ago. We did measurements together. ALL fluids behave the same way. They get thinner when they are heated, and thicken when they get colder. It's a law of physics.
Actually it is a measure of the specific DENSITY ot the fluid, and how it changes at various temperattures.
No, density and viscosity are related but they are not the same thing.
Atactic polypropylene. The molecule is a little ball, but when it gets hotter, the ball unrolls and the molecule turns into a long straight string. A solution of the stuff gets thicker when you heat it up, because the resistance to flow of the unrolled molecule is greater than the rolled up one.
Typical multigrade motor oils use this principle, although more popular now are proprietary ester polymers that form corkscrews that unroll instead of balls. VI technology is pretty nifty stuff.
You were wrong then, and you are wrong now if you think that the time you hold the fluid at a given temperature matters. The thickness measurements are taken *after* the fluid stabilizes at a given temperature.
Both Scott and I have said this. You are still missing the point. If you plot the curve of thickness vs temperature (no "time" axis comes into play), the viscosity index is the SLOPE of that curve. Different oils have different slopes (change thickness LESS as the temperature changes), and the less steep the slope the higher the VI and the wider the multi-viscosity rating can be.
NOTE: That FLUIDS (and NOT solids as you gave an example) behave
Let's start here since notation doesn't transfer to non-binary groups.
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's_law_of_cooling#Newton.27s_law_of_cooling
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If a compression or expansion takes place under constant temperature conditions - the process is said to be isothermal. The isothermal process can with the Ideal Gas Law be expressed as
p / ? = constant (1)
where
p = absolute pressure
? = density
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physics) The dimensional changes exhibited by solids, liquids, and gases for changes in temperature while pressure is held constant.
Most materials are subject to thermal expansion: a tendency to expand when heated, and to contract when cooled. For this reason, bridges are built with metal expansion joints, so that they can expand and contract without causing faults in the overall structure of the bridge. Other machines and structures likewise have built-in protection against the hazards of thermal expansion. But thermal expansion can also be advantageous, making possible the workings of thermometers and thermostats.
How It Works
Molecular Translational Energy
In scientific terms, heat is internal energy that flows from a system of relatively high temperature to one at a relatively low temperature. The internal energy itself, identified as thermal energy, is what people commonly mean when they say "heat." A form of kinetic energy due to the movement of molecules, thermal energy is sometimes called molecular translational energy.
Temperature is defined as a measure of the average molecular translational energy in a system, and the greater the temperature change for most materials, as we shall see, the greater the amount of thermal expansion. Thus, all these aspects of "heat"?heat itself (in the scientific sense), as well as thermal energy, temperature, and thermal expansion?are ultimately affected by the motion of molecules in relation to one another.
Molecular Motion and Newtonian Physics
In general, the kinetic energy created by molecular motion can be understood within the framework of classical physics?that is, the paradigm associated with Sir Isaac Newton (1642-1727) and his laws of motion. Newton was the first to understand the physical force known as gravity, and he explained the behavior of objects within the context of gravitational force. Among the concepts essential to an understanding of Newtonian physics are the mass of an object, its rate of motion (whether in terms of velocity or acceleration), and the distance between objects. These, in turn, are all components central to an understanding of how molecules in relative motion generate thermal energy.
The greater the momentum of an object?that is, the product of its mass multiplied by its rate of velocity?the greater the impact it has on another object with which it collides. The greater, also, is its kinetic energy, which is equal to one-half its mass multiplied by the square of its velocity. The mass of a molecule, of course, is very small, yet if all the molecules within an object are in relative motion?many of them colliding and, thus, transferring kinetic energy?this is bound to lead to a relatively large amount of thermal energy on the part of the larger object
Duhhh that's what I said. The molecular CHAINING in multi-weight oils do NOT change fluid properties, they alter only the TIME frame in which the changes occur. In other words - when the fluid (in this case motor oil) absorbs heat from the engine, a 10 W. 30 weight oil will thin to equivalent of a 10 weight oil in a longer span of time than a straight 30 weight would. But when both fluids attain the destination temperature their viscosity will be essentially the same as will their lubrication potential. The standard test for lubrication potential of motor oils has been for many decades to heat them to a specific temperature akin to the operating temperature of a motor oil in an average internal combustion engine. Then to apply pressure to bearings on a rotating shaft to determine at what point the oil loses its lubrication potential. Texaco for some years was running a TV ad comparing their Havoline 10 W 30 against other oil companies 10 w 30. My argument with the refinery engineer was along the lines that I thought Havoline straight
30 weight would actually perform better than the multi-grade. He said that they had never compared it to our own oils. He then performed the tests in the Texaco labs. He bought me the steak dinner.
That was before 10 W 40 and 10 W 50 came around and later 20 W 50. Long before synthetics which has a very improved lubrication potential. Recently Castrol's Edge deposed Mobil 1 as the champ. By a remarkable degree. I am sure that Mobil won't take that sitting down.
I never mentioned any solid and neither did Scott- he mentioned a non-Newtonian *liquid*.
What I have said is that the rate of change of thickness with temperature is different for different base oils. For example, shell XHVI Group III+ base oil (Rotella synthetic, Pennzoil Platinum) thins out FAR less as you heat it up than a garden-variety group II or III base oil (plain old Valvoline or Castrol non-synthetic, Pennzoil "yellow bottle", etc.) even before you start putting in additives. If you still deny this fact, then you're still wrong.
Its just like my water vs. honey example. Honey changes thickness a lot as you warm it up, water hardly changes at all. The XHVI base oil is more like water in that regard. So are the Group IV PAO base fluids that other synthetics like Mobil 1, Redline, Royal Purple, etc. use. And THAT is why multi-grade motor oils made from high VI base oils are superior to single-grade oils.
No that's NOT what you said. And look: you're about to say the same wrong thing again:
By definition a 10w30 and a 30 will be approximately the same thickness AT OPERATING TEMPERATURE (the rating is made at 100C). What matters is the fact that one thins out as you warm it up from a cold start (30 wt), the other more nearly stays constant (10w30).
Besides that, many modern multi-weight oils DO NOT DEPEND on what you call "molecular chaining" additives in order to achieve their thickness stability- it is just inherent in the base oil that it does not thin as much when you heat it as an older oil.
And with or without "chaining," you are missing the point that time is irrelevant. If you take a 10w30 oil and a 30 weight oil and hold them at
40 degrees C for a whole year before you measure the thickness, the 30 weight oil will be far, far thicker than the 10w30. Conversely, if you hold them both at 100 degrees C for a year and then measure the thickness, they will be about the same thickness. "Time" is irrelevant! The slope of the thickness/temperature plot is the issue.
No your wrong about that. The specification does not require them to be exactly the same but that only the difference to be within a specified amount. At 110C the difference in viscosity becomes significantly larger. 110C or higher would not be an unusual temp for oil in the average car on warm summer day. I don't know if that is what krp is trying to say or not. He is correct that 10w30 will be thinner than straight 30 in the typical car on a typical summer day.
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