Diesel engine oil is different from similar products for gasoline ICEs. The diesel engine runs on a lean air-fuel mixture, is heavily heat-loaded, the process of mixture formation and combustion of fuel in a diesel engine is accelerated. It is more difficult for a diesel engine to realize complete combustion of fuel in cylinders, the exhaust gases contain a large amount of soot. Diesel fuel itself has a high sulfur content.
High pressure in the combustion chamber leads to a more active breakthrough of gases into the engine crankcase, with which the crankcase ventilation system does not always cope. The result is an accelerated aging process of diesel engine oil, its oxidation and a rapid loss of protective, washing and other useful properties.
It is quite obvious that the life of any engine depends on the quality and maximum compliance of engine oil with respect to a specific type of engine. It is extremely important for diesel oil to maintain the stability of all optimum performance for as long as possible.
The main characteristics of diesel oils
Recommended classifications, parameters, tolerances and requirements for engine oil for a specific make and model of a car are usually indicated by the vehicle manufacturer in the instruction manual. For accuracy, you can also use the catalog for the selection of oils.
Almost every “diesel engine” seeks to purchase the best engine oil for diesel engines, and far from all of them understand the basic standards of engine oils. In practice, the independent selection of fuels and lubricants always begins with the question of which oil to fill in the diesel engine. Let’s take a closer look at how to choose the right diesel engine oil.
Today, various grades of diesel oils are widely represented on sale, which differ from each other in types, classes and standards. Just note that gasoline and diesel engine oil is mineral, semi-synthetic and synthetic. The oils are classified according to viscosity based on the SAE standard (from the English Society of Automotive Engineers). On the label of the canister with motor oil, the main emphasis is on markings such as 5W-40, 10W-40, etc. These data indicate the SAE viscosity grade. The first digit with the letter W (from the English winter. winter) indicates that the oil belongs to the low temperature class.
The ease of pumping oil through the oil channels of the engine lubrication system, its feed rate to rubbing surfaces, the battery charge and the degree of resistance when the crankshaft rotates with a starter during cold start directly depends on this indicator. For a diesel engine, oils with a rating of 5W (up to 25 ° C), 10W (up to 20 ° C), 15W (up to 15 ° C) are most relevant. The lower the number, the less viscous the oil will be.
The second digit after designating low temperature viscosity indicates a high temperature viscosity class. This class corresponds to the viscosity index of engine oil after warming up and the engine reaches its optimum operating temperature.
The API (from the American Petroleum Institute) is a standard developed by the United States Petroleum Institute. This standard separates oils according to their performance properties. The API standard divides engine oil into two broad categories:
- oils for gasoline ICEs belong to category S;
- diesel engine oil meets category C;
There is also a further division into classes and subclasses. As for the diesel engine, then by API diesel oils are often classified as CF. Such a product is suitable for operation both in atmospheric diesel ICEs and in turbodiesels.
ACEA (European Automobile Manufacturers Association) has put forward an additional set of its own requirements regarding the use of motor oils in engines. The two main categories for ACEA for cars are:
- category A (motor oils for gasoline engines);
- category B (motor oils for diesel engines);
The third category E is considered to be oils for heavy diesel trucks and powerful diesel engine. The fourth is Class C, which combines oils for diesel and gasoline engines, which are compatible with catalysts and particulate filters.
In addition, ACEA oils are divided into standard and energy-saving. Energy-saving class: A1 and A5 for gasoline engines, B1 and B5 for diesel engines of passenger cars and light-duty trucks. Other intermediate numbers refer to standard oils.
Universal oil for diesel and gasoline
There are also “universal” oils that can be used simultaneously in both gasoline and diesel engines. These products are fully compliant with API and ACEA standards. Such oils are marked with the same categories S and C, but with a slight reservation.
The inscription SJ / CF on the canister label with engine oil indicates that the oil is universal, intended for gasoline and diesel engines, but its use is priority in gasoline units. The CF / SJ mark indicates that it is preferable to use such engine oil in a diesel engine.
This issue has forced car manufacturers to do more research. Ford Motor Company specialists analyzed the properties of oils when driving on Turkish diesel fuel. The sulfur content in this diesel engine is up to 20 times higher compared to the fuel from Western Europe. By the way, this experience can be successfully applied to the CIS countries. The study used various oils by grade. ACEA A1 / B1 has also been tested, which is a universal oil for equivalent use in gasoline and light diesel cars. This oil is universally recommended for diesel engines in European countries with high-quality fuel.
Analysis of the decrease in alkaline number when driving in Turkish diesel fuel revealed the moment when the universal oil ceases to protect the diesel engine from the acidic environment, denoted by TAN. In other words, after how many kilometers, the acid number grew to the point where the real oxidation process began and, consequently, the wear of the diesel engine.
Based on the data, the researchers came to the conclusion that, with the use of universal motor oil and low-grade diesel fuel, the increase in the acid number began to exceed acceptable values after about 5-6 thousand kilometers traveled. The most optimal when driving on a bad diesel engine turned out to be special ACEA B3 / E3 diesel oil, which is recommended for highly accelerated diesels and heavy trucks.
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It is also worth considering that cold start, winter warm-ups and idle downtimes from the “Turkish” test were excluded. In our realities, the quality of diesel fuel at domestic gas stations leaves much to be desired. It can be assumed that in the CIS, universal gasoline / diesel oil on city cars will need to be changed every 4 thousand kilometers.
Energy Saving Engine Oil: What You Need to Know
The main purpose of the so-called energy-saving oils is fuel economy. Less fuel consumption means more environmentally friendly motor. Reduced consumption is achieved due to the maximum reduction of friction losses during engine operation. The HT / HS indicator, which indicates the viscosity of the oil at high temperature and high shear rate, determines this property of motor oil.
Standard oil at a temperature mark of about 150 degrees Celsius retains sufficient viscosity, which allows for full protection of loaded parts of the power unit. A reduction in viscosity under similar conditions allows engine parts to interact with less loss, resulting in fuel economy. In fact, the thickness of the oil film decreases with increasing temperature of the internal combustion engine, the motor spins more easily, but the protection of parts from wear also weakens.
In such ICEs, the oil channels are narrow, the lubrication system requires a lower viscosity to create the desired oil pressure in the diesel engine and effectively supply it to the loaded friction vapors. Also, it is definitely not worth using energy-saving oil in old gasoline and diesel engines.
Guidelines, standards and approvals from leading manufacturers
In the owner’s manual, each automaker for its engines specifies tolerances based on SAE, API and ACEA standards for engine oil. For turbodiesels from 2004 with a particulate filter:
- Japanese Mitsubishi and Mazda define ACEA standard B1;
- brands Toyota (Lexus), Honda (Acura), Fiat, Citroen, Peugeot allow the use of oil, which according to ACEA corresponds to the category from B2 and higher;
- The Renault-Nissan Alliance defines ACEA requirements for motors as B3-B4;
Korean auto giant Hyundai / Kia recommends ZIC oil (XQ LS). Ford manufacturer for engines of the Zetec line indicated oil under its own brand with the index М2С 913. For turbodiesels from 2004 with a particulate filter, Ford defines diesel engine oil М2С913С. Another variant of the recommended oil is the Ford 934 index.
Volkswagen manufacturer even separately allocates a brand of engine oil VW 507 00 Castrol for turbo-diesel engines of its concern, which were produced before 2004 and have a particulate filter. Units are installed on Volkswagen, as well as subsidiary models of Skoda and Seat.
GM brands (Opel, Chevrolet, etc.) that are part of the corporation, for turbocharged diesel engines from 2004 with a diesel particulate filter, are prescribed to use Dexos 2 engine oil. Opel engines up to 2000 ACEA are allowed to use A3 / B3 oil. Motors after 2000 can drive in oil with a GM-LL-B-025 approval.
German Volkswagen is followed by BMW. The company also recommends the use of Castrol oils or engine oils that match its tolerances under the BMW Longlife brand of its own. This requirement is especially true for motors equipped with variable valve timing systems. The channels for supplying grease to the “phase shifter” are very narrow, so the use of third-party oil is not recommended due to the risk of coking. For BMW turbodiesels manufactured before 2004 and equipped with a particulate filter, the recommended oil is BMW Longlife-04.
TDI motors that are installed on an Audi from Volkswagen concern have the following oil tolerances:
- engines until the year 2000. index VW505.01;
- engines 2000-2003. 506.01;
- units after 2004 have an oil index of 507.00;
The Mercedes-Benz concern for diesel engines after 2004, equipped with a particulate filter, provides engine oil under its own brand with the index 229.31 and 229.51. One of the highest tolerances for engine oil for diesel ICEs is the index from 504.00 to 507. 00. It is recommended to use engine oil marked CF-4 in diesel trucks.
An excellent example is Liqui Moly engine oils, whose products often not only fully comply with all necessary tolerances, but even exceed them. The only disadvantage is the rather high cost of such products.
Which oil is better for a turbodiesel
In the process of operating a diesel engine, the owners, for obvious reasons, try to select the best oil for diesel turbocharged engines or atmospheric versions of different years of production. At the same time, both foreign products and Russian oils for diesel engines are presented on the market today.
The variety of oils allows you to choose the best solutions for different diesel engines (for example, diesel engine oil with a diesel particulate filter, winter diesel engine oil or summer oil, long-range diesel engine oil, air-cooled diesel engine oil, etc. ) Given that turbodiesel is the most common today, let’s start with this type of ICE.
So, for a turbodiesel, you can select oil Lukoil, Liqui Moly, Mobil, as well as Castrol. Considering that the lubricant works under conditions of active pollution, high heating and rapid oxidation (due to the large volume of incoming air with various particles, the presence of sulfur in diesel fuel, etc.), the oil in a diesel engine should have high stability.
To choose a turbodiesel oil, you need to pay attention to the basic base (synthetics or semi-synthetics), as well as the classification according to SAE. The base of the oil allows you to understand how often you will have to change such a lubricant, as well as how the oil will manifest itself in conditions of high and low temperatures.
Synthetics retains their properties longer, does not “get stuck” in the cold and nurses the declared service life without a noticeable loss of properties. However, when heated, this oil can be “liquid”, which on older engines can cause leaks. Semi-synthetics has a shorter resource, it can be pumped out a little worse during severe colds at startup, however, it doesn’t liquefy so much when heated, and also costs less.
We also add that it is better to refuse universal cheap oils such as gasoline / diesel or diesel / gasoline, acquiring products originally designed only for use in a turbocharged diesel engine. It is also important to pay attention to the tolerances of the engine manufacturer itself.
If we talk about the choice, Lukoil oil for turbodiesel is a common and popular domestic product. Well proven and diesel oil Liqui Moly. The product is expensive, but a unique additive package allows this oil to effectively protect a loaded engine and save the resource of the unit in difficult conditions.
Mobil oil for turbodiesel, as well as Castrol for turbocharged diesel engines are considered one of the best options in terms of quality and price. We also add that Castrol for a turbodiesel in the Russian Federation has long been one of the most sought-after solutions. Unfortunately, given the great popularity, today the risks of running into a low-grade fake have significantly increased. This also applies to other popular manufacturers.
Useful tips when choosing oil in a diesel engine
Based on the above information, you can answer the question of how to choose diesel oil and which oil is better to fill in a diesel engine. If the car is relatively new and is under warranty, then it is recommended to fill in diesel oil sold in the network of official dealership service stations. You need to select an oil on your own, which most closely matches all the tolerances of the car manufacturer according to SAE, API and ACEA.
Sometimes diesel oil is called “winter”, “summer” and “all-weather”. For a diesel engine, which is in extreme extreme seasonal temperatures (extreme heat in the summer and great frost in the winter), the conditional “seasonality” of the oil can make a difference. The resource of the motor will be reduced during year-round driving in oil, the upper and lower threshold of temperature viscosity of which is far beyond in relation to actual operating conditions. A diesel engine will constantly face difficult start-up in winter and increased wear of parts in summer in such regions with large temperature fluctuations. For special cases, oil changes are practiced seasonally.
Winter diesel oil has the lowest viscosity. This is necessary for a normal cold start. Summer diesel oil is more viscous and provides reliable protection in the form of an oil film on friction vapors in the heat. In other cases, the last group of “all-season” motor oils is most widely used due to its versatility.
The best choice for a diesel engine, which is constantly operated on diesel fuel of dubious quality, will be the use of diesel oil with an alkali index of TBN 8-10 compared to universal oil for simultaneous use in gasoline and diesel engines, which has an indicator of 6-7. Otherwise, the replacement interval for the specified universal motor oil for a diesel engine will need to be reduced at least twice.
The last recommendation is to take into account not only the kilometers traveled from replacement to replacing engine oil in a diesel or gasoline engine, but also the so-called “hours” that the engine worked at idle. Continuous operation of the engine in idle mode refers to difficult operating conditions, which causes accelerated oil aging. If the car is idle for a long time with the engine running, then it is conditionally worth adding from 1 to 3 additional “conditional” thousands to every 10 thousand kilometers actually traveled. A more accurate figure will depend on the specific individual operating conditions of the vehicle.