Basic knowledge of engine oil seen from big data
Car engines are often compared to the human heart. Engine oil is likened to the blood that flows through the heart. In other words, it can be said that engine oil is one of the most important maintenance supplies for a car.
The five major effects of oil are used to explain the functions of engine oil. There are five functions: (1) lubricating action, (2) sealing action, (3) cleansing and dispersing action, (4) cooling action, and (5) antirust/anticorrosion action.
Even if one of these five functions is lacking, the engine will suffer. While the engine is running, the oil is constantly exposed to high heat and gradually oxidizes.
Additionally, water, carbon, and sludge (dirt residue generated as a result of combustion) are mixed in, and the original function is also impaired.
The blood that flows through the human body produces blood while carrying out carbon dioxide and waste products to keep it fresh, but engine oil does not have such a function. Dirty engine oil must therefore be replaced.
In other words, engine oil plays an extremely important role in protecting the engine itself.
Exploring the actual state of the engine oil market from dealer big data
However, in recent years, the importance of it has been imposed less and less.
In recent years, the development of fuel-efficient engines and the reduction of engine displacement have progressed due to the growing awareness of environmental conservation.
In order to achieve low fuel consumption, it is important to use low-viscosity oil that does not put a load on the engine, as well as how to drive.
By the way, the recommended oil viscosity for Toyota's new Prius scheduled to be released in December this year is "0W-16", which is even lower than "0W-20" for the conventional 30-series Prius.
In order for the new Prius to achieve the world's highest fuel efficiency of 40km/ℓ, ultra-low-viscosity oil that draws out the potential of the engine is essential.
In other words, even if it is an eco-friendly car, if the engine oil is not suitable for it, the low fuel consumption performance cannot be fully demonstrated.
So, here again, how are the recent changes in the composition of vehicle types linked to the selection of engine oil, including the basic knowledge of engine oil, the need for oil changes, and the proper cycle of replacement timing? of We will verify it by comparing it with the real data of the AUTOBACS Group, which has a track record of 5 million engine oil changes per year.
[1] Basic knowledge of engine oil 1-1. Types of Engine Oil Engine oils are roughly divided into two types, one for gasoline engines and the other for diesel engines.
Both have almost the same basic performance, but diesel engine oil contains a large amount of alkali as an additive to neutralize acid.
This is because diesel engines use light oil for fuel. Diesel oil contains sulfur, and when it burns, it becomes sulfur oxide, and this acid corrodes the inside of the engine.
In order to prevent corrosion, it is necessary to neutralize the acid with alkali. Incidentally, according to oil manufacturers, the ratio of gasoline to diesel vehicles in the domestic market is nearly 9:1, with gasoline vehicles occupying an overwhelming majority.
So, first of all, I would like to explain engine oil for gasoline cars.
1-2. Engine oil manufacturing method Engine oil is made by adding additives to base oil refined and extracted from crude oil.
There are three types of base oil: synthetic oil, semi-synthetic oil, and mineral oil. Synthetic oil is a high-quality oil made by chemically decomposing mineral oil and chemically synthesizing additives for engine cleaning and the environment.
By keeping the composition and molecular weight constant, it exhibits stable performance under all conditions, including heat resistance, long life, and excellent startability at low temperatures. However, the cost is high.
Semi-synthetic oil is a base oil in which 20% to 30% of chemically synthesized oil or hydrorefined oil is mixed with mineral oil, and is highly economical. However, heat resistance performance is not as good as synthetic oil.
Mineral oil is a base oil refined from crude oil. Because it contains impurities, the shape and size of the oil particles are non-uniform, leaving particles that cause stains and wax that hardens at low temperatures, resulting in unstable performance. On the other hand, it has the advantage of being cheap.
Engine oil in various price ranges are lined up at oil stores and gas stations, but the price difference is determined by which of the above three types of base oil is used.
By the way, the low-viscosity oil, which has been increasing in recent years, is often a little more expensive than the normal-viscosity oil. This is because many of them use chemically synthesized oils as base oils.
1-3. About the 5 roles of engine oil Engine oil is usually contained in the "oil pan" attached to the bottom of the engine, and is pumped up by the "oil pump" and sent to various parts of the engine.
Engine oil is known as a lubricating oil, and its lubricating action is well known, but in fact, it has various other functions.
These are the 5 major effects of oil.
(1) Lubrication By creating an oil film between metals, metals do not touch each other directly, reducing frictional resistance and reducing energy loss. (2) Sealing action Seal the gap between the piston and the cylinder with an oil film to prevent the pressure of the combustion gas in the cylinder from blowing through to the crankcase side. (3) Cleansing and dispersing action Carbon and sludge generated inside the engine are dispersed in the oil as minute particles without depositing and accumulating in each part. (4) Cooling action Cools the engine by removing frictional heat inside the engine and heat generated by combustion of fuel. (5) Anti-rust and anti-corrosion action Protects the engine from the acid and water generated inside the engine, preventing the occurrence of rust and corrosion.
Engine oil performs various functions in harsh conditions, so deterioration is inevitable.
That's why engine oil needs to be changed regularly.
1-4. About the engine oil replacement cycle Engine oil, which performs the five major functions mentioned above, gradually deteriorates due to oxidation due to heat, as well as contamination with water, carbon, dirt, dust, metal abrasion powder, etc.
Deteriorated oil tends to cause various troubles such as overheating, power down, reduced fuel consumption, and noise. To prevent these problems from occurring, it is necessary to change the engine oil regularly.
As for the regular change cycle of the engine oil, the guideline is the mileage and period written in the owner's manual of the car, and the recommendation of an experienced and reliable engine oil dealer.
In addition to this guideline, another thing to consider is the usage of the car. What conditions do you usually use your car in? Drivers need to understand this.
"Severe Condition" and "Normal Condition"
Usually, the usage status of a car can be roughly divided into two types, "severe condition" and "normal condition".
Severe conditions are cases where you often drive on rough roads such as gravel roads, snowy roads, and unpaved roads, or when you drive long distances exceeding 20,000 km per year.
However, frequent use of unfavorable conditions for the engine, such as repeated short-distance driving, low-speed driving, and frequent idling, are also classified as severe conditions.
In other words, not only is the engine overworked by running long distances, but even the state of almost no running is a favorable usage condition for the engine and engine oil.
Severe conditions may accelerate the deterioration of parts, so the replacement cycle is said to be shorter than the manufacturer's recommended value.
Conversely, normal conditions refer to conditions of use that do not fall under these severe conditions.
The guideline for the engine oil change cycle in severe conditions is half the mileage and period of the cycle recommended by the automobile manufacturer. To which side does the driver belong in terms of usage of his/her car? always have to be aware.
1-5. About the viscosity of the engine oil Next, how to choose the engine oil, most recommended oils are listed in the instruction manual of the car.
Because engine oil has a viscosity suitable for the engine of the car. The SAE standard established by the Society of Automotive Engineers (SAE) is widely used as a standard that indicates the viscosity of such oil.
It is the standard that is written as "0W-20" or "5W-30" on the can of engine oil.
For example, in the case of the viscosity display "0W-20", the number before W (abbreviation for Winter) represents the viscosity at low temperature (when the engine is started).
The lower the number, the harder it is for the oil to harden even at low temperatures. On the other hand, the number after the hyphen indicates the viscosity on the high temperature side (running state).
The higher the number, the higher the viscosity. Even if the engine becomes hot, the oil does not become dry and maintains its viscosity to protect the metal friction surface.
In other words, if the number is small, the oil is smooth and soft, and if the number is large, the oil is sticky and hard.
Oil viscosity depends on outside air temperature and engine combustion temperature
Oil originally has the property of being hard at low temperatures and becoming soft at high temperatures.
For example, if you put salad oil on a cold frying pan, it will be sticky, but if you put it on a heated frying pan, it will spread smoothly.
Similarly, the engine oil is cold when the engine starts, so normal oil becomes hard. Oil that is still hard increases resistance to the pistons and crankshaft inside the engine.
When starting the engine of a fuel-efficient car, automobile manufacturers recommend using a smooth, low-viscosity oil that is less sticky, because they want to reduce resistance to pistons and improve fuel efficiency.
For example, hybrid cars and idling stop cars start and stop the engine more frequently than normal cars, so there is a risk of dry start (starting without oil film inside the engine). be.
A low-viscosity oil that circulates quickly even when the engine is started is preferable in this regard.
On the other hand, for sports cars that rev the engine at high speed, there is a risk that the metal wear surface of the engine will be destroyed if the oil is not hard enough to maintain its viscosity.
That's why you shouldn't use smooth, low-viscosity oil in sports cars.
When choosing engine oil, you can not only choose the oil with the viscosity that suits your car, but also consider the usage conditions of your car, and you can keep your car comfortable for a longer time.
[2] Changing engine oil selection In response to the recent increase in environmental awareness, the automobile industry in Japan has developed hybrid cars, plug-in hybrid cars, electric cars, fuel cell cars, and light cars, which are eco-friendly cars unique to Japan. Research and development is progressing by branching into a wide range of categories.
Gasoline engine cars still dominate the number of cars owned, but hybrid cars and light cars are increasing their share remarkably. They are characterized by their superior environmental performance and economic efficiency, which is also the reason for their popularity.
Ten years ago in 2005, the share of light cars in the number of cars owned was only 24.9%. However, in 2014, the market share increased to 34.6%.
The increasing share of light vehicles is well reflected in Graph 1, “Transition of sales volume composition ratio by engine oil liter can”.
The 3L can of engine oil is the capacity purchased by users of light and compact cars, and the 4L can is the capacity mainly purchased by users of small passenger cars and ordinary passenger cars.
In fiscal 2010, the sales ratio of 3L cans at retailers was 29.8%, but four years later in fiscal 2014, it was 41.2%, an increase of 11.4 points.
Nowadays, it is no exaggeration to say that fuel-efficient cars are a prerequisite for choosing a car, and it seems that car manufacturers are also taking this as a prerequisite for vehicle development.
2-1. With the rapid increase in the number of eco-friendly vehicles, low-viscosity oil plays a leading role in the development of eco-friendly vehicles, and automobile manufacturers are using low-viscosity oil as genuine products in order to appeal their low fuel consumption performance.
Actually, at the new car stage, 0W-20, or depending on the manufacturer, ultra-low viscosity oil such as 0W-16 or 0W-8 is used as genuine oil.
Therefore, when changing the oil, it is necessary to look at the instruction manual and know the viscosity of the oil that suits your car.
For example, in the case of the conventional Prius (30 series), the instruction manual lists four viscosities of oil: 0W-20, 5W-20, 5W-30, and 10W-30.
You can use any of these viscosities, but the manufacturer recommends 0W-20. The reason for this is to maximize fuel efficiency.
Low-viscosity oil keeps the oil smooth and soft even on freezing mornings in the middle of winter.
When the oil hardens in the cold, the resistance to starting the engine increases, but if it does not harden, the resistance is small and fuel economy does not deteriorate.
Conversely, low-viscosity oil is not suitable for sports cars and other vehicles that rev the engine at high speeds. This is because if the resistance that acts as a cushion inside the engine is lost, the engine could be destroyed.
For such cars, high-viscosity oils with large numbers at the end, such as "0W-30" and "10W-50", are suitable.
Currently, 90% of new cars on the market are equipped with fuel-efficient engines, and in 2014, industry estimates show that 68% of recommended oils for new passenger cars are 0W-20, and low-viscosity oil. 0W-16 and 0W-8 are 25%, and the total is 93%.
If the number of vehicles that recommend ultra-low viscosity oil increases, like the new Prius mentioned above, 0W-20 will one day be replaced by 0W-16 and 0W-8.
On the other hand, oil manufacturers estimate that the number of passenger cars equipped with fuel-efficient engines exceeds at least 60%.
Similarly, if the sales ratio of low-viscosity oil is about 60% of the total, it will be an environment where the original environmental performance of the car can be easily demonstrated, but in reality, it has not yet reached that level.
Standards for sales oil that show discrepancies with actual car model sales
Graph 2 shows the sales composition ratio of 0W-20 (3L, 4L cans, not including sales by weight) of oil sales volume by viscosity sold by the AUTOBACS Group in 2014.
The composition ratio of 0W-20 sales (3L and 4L cans, not including sales by weight) was 41.8% of the oil sales volume by viscosity sold by the company in FY2014.
If we look at 60% of the total number of vehicles equipped with fuel-efficient engines in Japan, AUTOBACS' sales ratio of low-viscosity oil is 40%. In other words, there is a difference of 20% from the estimated number of vehicles owned.
About this 20% difference, it is said that personal interpretation of the recommended viscosity, lack of awareness, and resistance to price increases (some reduction in fuel consumption is covered by cheap oil prices) are having an impact. Conceivable.
By the way, looking at the retail price (as of December 1), the 4L can of oil from the private brand "AQ." is 0W-20 (partially synthetic oil) for 3,980 yen (tax included). 10W-30 (mineral oil) is 2,180 yen (tax included), with a price difference of 1,800 yen.
The price of oil varies from store to store, but low-viscosity oil is generally more expensive. According to the oil manufacturer, this price difference is due to ``0W-20, which often uses chemically synthesized or partially synthetic oil as its base oil, while 5W-30 and 10W-30 often use partially synthetic or mineral oil, That is reflected in the price,” he said.
In the future, 0W-20, which was classified as low-viscosity oil, will be classified as ordinary oil, and if it becomes a volume zone more than now, the price difference will gradually disappear.
In fact, the sales composition ratio of 0W-20 in 2010 in Graph 2 was 25.6%, but since then it has risen every year, and since 2013, the sales volume has exceeded 5W-30.
2-2. Turbocharged vehicles for improved fuel efficiency are on the rise Another change in the environment surrounding engine oil is the increasing number of vehicle models that use turbochargers (superchargers powered by turbines) that achieve both low fuel consumption and increased power. .
Turbo, which sends a large amount of air with a supercharger, increases the thermal efficiency of the engine compared to non-turbo (naturally aspirated), so it can draw out a large amount of power.
In Japan in the 1980s, it gained popularity for the purpose of powering up sporty cars, but its ratio decreased in the early 2000s due to reasons such as the engine being prone to abnormal combustion. However, in recent years, after technological innovation, it has been revived.
The main purpose of the turbo currently installed is to compensate for the power loss of the engine, which has been downsized in consideration of the environment, rather than just increasing power like before.
The downsizing of the engine in Germany's VW's main model "Golf" created the flow of today's turbo. In recent years, the Golf has been downsizing the displacement of the engine with each model change to improve fuel efficiency.
For example, automakers claim that by installing a turbo even in a 1,400cc engine, the power can achieve 2,000cc class driving.
Hybrid cars are the mainstream of eco-friendly cars in Japan, but depending on the manufacturer, mainly European cars, hybrid cars, which are costly, are limited to some and downsizing is promoting low fuel consumption.
Turbo cars have no problem in terms of power, but the condition is severe for the engine, and the oil deteriorates quickly.
Downsizing accelerates the increase in turbo cars
Each automaker sets the oil change cycle (mileage, period) of turbo cars to half that of non-turbo cars, and enlightens them in instruction manuals and websites.
In recent years, turbo specification vehicles have been added to Honda's Step Wagon, Toyota's Auris, Nissan's Skyline, and Fuji Heavy Industries' Levorg.
In particular, the displacement of the step wagon has been reduced from 2,000cc to 1,500cc, but the acceleration capacity is on par with 2,400cc.
In addition, minicars are more turbocharged than registered cars. The sales ratio of mini vehicles in new car sales was almost 40%.
One of the reasons why kei cars are supported is the size of the living space that you can't think of as kei. The spacious space was realized by tall (height) wagons with a total height of over 1,600mm, which now accounts for 70% to 80% of the mini vehicles sold as new vehicles.
However, the larger the car, the heavier the car. The lightest Suzuki Alto is in the 600kg range, but Honda's N BOX + Custom, Daihatsu's Wake, and tall wagons with 4WD specifications weigh around 1 ton.
This is almost the same as the registered car Aqua and Demio. It is undeniable that the normal 660cc engine lacks power, and a turbo was introduced to make up for it.
The sales ratio of turbo cars varies depending on the car model, but according to Daihatsu, for example, wake accounts for nearly 70%.
When a light car becomes a turbo specification, the vehicle price is never cheap. However, users who have ridden a turbo car even once cannot return to a weak non-turbo mini car, and will always choose a turbo car next time.
However, the turbo car is treated the same as the severe condition car mentioned above. The guideline for the oil change cycle is 1/2 of the normal condition for both mileage and period.
Even if it is the same vehicle, the recommended replacement timing of the engine oil will differ depending on how it is used and whether it has a turbo.