Motor oil is an oily substance that is used to maintain vehicle parts. In addition, modern oils are also responsible for cleaning engine parts from combustion products. So, At what temperature does motor oil freeze?
In reality, there is no freezing of oil, since it does not freeze at natural temperatures. That is to say, it practically cannot freeze like water does, but more simply, it thickens. Sometimes many drivers find it difficult to start the engine in severe frost even if the battery is new and there are no faults, because the engine starts with great difficulty.
And the culprit for this may be motor oil that thickens at subzero temperatures. That is why it is important to know at what temperature engine oil freezes or as it should be said, at what temperature it thickens and here we will talk to you about everything related to it.
Why does oil thicken?
In motor oils, the composition and viscosity significantly influence the way in which said oil thickens at subzero temperatures. However, all engine lubricants can literally turn into a stale and viscous composition in severe frosts.
Which causes the engine to jam from the inside, causing difficulties in achieving a smooth or regular start of the vehicle. And inevitably trying to do so could cause ignition starting problems and the battery would discharge very quickly.
Technical characteristics of motor oils
As we mentioned before, the composition greatly influences understanding at what temperature motor oil freezes, but what are the characteristics of the oil? Well, they are determined by the ability of the liquid material to resist flow to the internal friction of the engine.
This can be calculated by the value it has in different conditions as you will see below:
The viscosity of lubricants changes inversely with temperature. For example: When oil is heated, its quality generally decreases and when it cools it increases. In products of different brands, the change of characteristics occurs at different rates.
There is a special concept to measure dynamics and it is the viscosity index. Basically, the higher their value, the less they will depend on temperature to maintain their efficiency. Because of this, products with a high rating provide reliable engine protection in extremely low-temperature conditions.
On the other hand, oils with a low viscosity value generally operate in a narrower temperature range, since when the materials they contain are heated they lose their lubricity and when they cool, they thicken quickly. That being said, there are two ways to measure the viscosity capacity of the oil.
This indicates the ability of a material to resist flow under the influence of gravity. It is measured in “Stokes, (St)” or differently in square millimeters per second (mm 2 / s). Most often, these characteristics are determined for temperatures of 40 and 100 centigrade.
Defines the relationship between force and cutting speed. This characteristic shows the ability of the engine oil to flow at different temperatures, these measurements are called as “cent poise”, (Cp)” or in (N • s / cm 2).
This indicator can be used to determine when the viscosity of the oil increases to the point of loss of fluidity. In this case, in laboratory conditions, the pour point is determined at the lower limit at which the liquid in a test tube with an inclination of 45 degrees does not drain within 1 minute and remains stationary.
For this reason, the low-temperature characteristics to know at what temperature motor oil freezes depend directly on its composition or, in reference to the quality of the components. In the case of petroleum products, the viscosity increases with the crystallization of normal paraffins.
Therefore, the base of its composition is subjected to deep cleaning and also a chemical modification to branch its structure and lower its pour point. In the case of synthetic oils, they have a more uniform and predictable composition, which reduces the crystallization threshold and provides the material with stable properties in frost.
The value of this characteristic depends on the type and amount of volatile fractions in the oil composition. The flash point indirectly indicates the loss of oil through waste.
Practically it is evaporation through the crankcase ventilation system. The parameter also allows you to evaluate the risk of spontaneous ignition or explosion of the material during extreme heating.
Total Base Number (TBN)
The total alkalinity of a motor oil depends on the characteristics of the dispersant and detergent additives, as well as the antioxidant properties of the material. The parameter indicates the resistance of the product to oxidation at high temperatures and pressures in the presence of reactive media.
Therefore, this characteristic is determined by a base number. This is measured in (mg KOH / g). The values of the numbers vary over a wide range. The choice depends on the type of sulfur content, which is the main oxidizing agent.
For example, in engines running on fuel oil, a high degree of protection is required, so an oil with an alkalinity index of up to 40 mg KOH / g is chosen. And for large car engines like passenger cars, they work with materials of 7 to 15 mg KOH/g.
Sulfated ash is formed when lubricant burns. Base oils are refined and virtually ashless, but additives usually introduce undesirable impurities such as magnesium, calcium, phosphorus, zinc, and others into the composition.
Therefore, in the combustion process, substances on the surfaces of engine parts cause dirt deposits to form that contribute to premature ignition of the fuel mixture.
On the other hand, ash also contaminates catalytic converters and particulate filters in the exhaust. Consequently, the lower this value is, the fewer slag deposits it will open on the parts.
What oil should you choose?
When it comes to choosing a suitable oil, the first thing you should consider is the weather conditions in which you are or are going to be. That is, if the place is very cold or hot since this will also depend on what temperature the motor oil freezes at. Also, keep in mind to read the instructions for use.
With this in mind, you make sure that the oil you choose is compatible with your vehicle and this will prevent it from thickening. In addition to avoiding serious damage to it. That said, all modern oils can be divided into three types:
The mineral is the cheapest and is made from crude oil, using already obsolete technology. Its main disadvantage is that this oil responds poorly to changes in temperature regime. Thus, it is the most prone to thickening, so you should know at what temperature motor oil freezes.
In this type of oil, with an increase in the temperature threshold, the additive begins to burn, and with a decrease, the composition acquires a viscous consistency, which significantly reduces the efficiency of the mechanisms.
Semi-synthetic is the same as mineral oil but diluted with synthetic additives. This is an intermediate option between synthetic and mineral. It is usually preferred in cases where the car has high mileage, which avoids the appearance of a factor such as the increased carbon content characteristic of synthetics.
In addition, semi-synthetics may be preferred in those conditions where the temperature threshold does not drop below 20 degrees. But you will have to change this more frequently.
Synthetic lubricant is made from the products of primary oil distillation. This is the most modern type with good features, but it should be noted that it is quite expensive. Synthetic oils simply eliminate carbon deposits.
High fluidity and this approach to cleaning often lead to clogging of filters, and oil lines, which leads to engine failure due to the very lack of the oil itself. But synthetics are still considered the best option.
What oil to use in winter or multipurpose?
In the course of our article, we have been talking about “at what temperature does motor oil freeze” well-known as the thickness or thickness of said oil. Now that we have explained the basics on the subject, we will talk to you about the letter and number marks that are printed on the oil bottle itself and their meaning so that you can choose correctly:
There are motor oils on sale that are designed for use only in subzero temperatures. For example, a lubricant that operates in the -10 to -40 mode is labeled SAE 0W, while one that operates in the 0 to -15 mode is labeled SAE 15W. But in urban conditions, it is impractical to use such oil, since thaws are more frequent.
On the other hand, the SAE J300 classification of viscosity-temperature properties of lubricants was developed by the American Society of Automotive Engineers. The W brand (winter) It is intended for materials that operate at low temperatures
The pumpability limit that is the MRV test (Mini Rotary Viscometer) and the starting capacity which is the CCS (Crankshaft Cold Start Simulator), are additionally regulated.
On the other hand, for summer varieties, shear resistance under extreme heating is determined with this test. (HTHS – High Temperature Shear Rate). The SAE J300 viscosity grade indicates the operating temperature range of a particular brand of motor oil.
Continuing with the topic, the designation of varieties of oils for all seasons combines have two indicators (winter and summer). For example, 5W-40. The Oil (synthetic) is marked “0W” and then there are numbers, (after letters) that mean the (minimum) temperature at which it can be operated. An example is Toyota 0W-30 motor oil.
There is also an oil that retains its characteristics even at -40 degrees below zero. This (again synthetic) labeled “5W” can be operated at temperatures up to -25 below freezing point, although it is also important that the manufacturer takes into account the approximate figure of -25.
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