Understanding what types of oils there are is fundamental to long-term operation of your car's engine. An error in choosing a lubricant can lead to accelerated wear of rubbing pairs, the formation of scoring, and even complete failure of the unit. The modern market offers a huge range of products, and it can be difficult even for an experienced driver to understand it the first time.
In this article we will analyze in detail the basic types of bases, viscosity classifications and international quality standards. You will find out what synthetics differs from mineral water, why it is important to pay attention to the manufacturer’s tolerances and how to choose the right product for the operating conditions of your region.
The correct choice of lubricant is not just marketing, but an engineering necessity. Modern car engines operate in extreme temperature conditions, and only high-quality oil can provide protection in such conditions.
Classification by type of base
The first thing to start with is the basic foundation of the product. It is this that determines up to 80% of the properties of the final liquid and its cost. There are three main types of bases, each with its own unique characteristics and applications.
Mineral oils are obtained by direct distillation of petroleum. This is the most affordable option, which is often called “mineral water”. However, such products have a significant drawback: they quickly oxidize and lose their properties at high temperatures. Mineral base has an unstable molecular structure, which leads to rapid waste and the formation of deposits.
Synthetic oils are created artificially in laboratory conditions. Their molecules have the same size and structure, which ensures excellent fluidity even in severe frosts. Synthetic base does not evaporate at high temperatures and holds the load perfectly. This is the best choice for modern turbocharged engines.
Semi-synthetics are a mixture of mineral and synthetic bases. Typically the share of “synthetics” in such a product ranges from 30% to 50%. This is a compromise solution that improves the characteristics of mineral oil while maintaining a relatively low price. Such fluids are often poured into high mileage engines.
When choosing a base, it is important to consider the condition of the motor. If the engine is old and has natural wear and tear, switching to pure synthetics can lead to oil seal leaks due to the high detergency and fluidity of the fluid.
⚠️ Attention: Never mix oils on different bases unless absolutely necessary. A chemical reaction between additives from different manufacturers can lead to the formation of sediment, which will immediately clog the oil filter.
Seasonality and SAE viscosity
The second critical parameter is viscosity. It shows how thick the oil remains at different temperatures. The international classification SAE (Society of Automotive Engineers) divides all products into winter, summer and all-season.
Modern drivers practically do not use monograde oils (only summer or only winter). The de facto standard is all-season liquids, the marking of which contains two numbers, for example, 5W-40. The first number with the letter W (Winter) indicates winter properties, and the second - summer properties.
The lower the number before the letter W, the lower the temperature at which the oil remains fluid. For example, 0W guarantees engine cranking down to -35°C, and 10W - up to -25°C. The second number indicates the viscosity at engine operating temperature (100°C). The higher it is, the more durable the film the oil creates.
For temperate climates, viscosity is considered the most universal choice 5W-30 or 5W-40. These indicators are suitable for most gasoline and diesel units, providing easy starting in winter and reliable protection in summer.
Check the dipstick only on a warm engine after 5-10 minutes of parking. Cold oil takes a long time to drain into the crankcase, and the readings will be incorrect.
Incorrectly selected viscosity leads to serious problems. Oil that is too thick will not have time to lubricate the components during a cold start, and oil that is too thin will not create a protective film under load.
International quality standards API and ACEA
In addition to viscosity, there are quality standards that regulate the set of additives and environmental properties. In the world, the American API specification and the European ACEA are considered the most authoritative.
The API standard divides oils into two large groups: S (Service) for gasoline engines and C (Commercial) for diesel engines. The designation consists of two letters, where the second indicates the generation of the standard. The further the letter is from the beginning of the alphabet, the more modern the product. For example, API SN is newer than API SG.
The European ACEA has more stringent requirements, since operating conditions in Europe differ from those in the United States. Environmental friendliness, compatibility with catalysts and the ability to operate at high speeds on the autobahn are important here.
The table below shows the breakdown of the main ACEA classes:
| Class | Description | Engine type |
|---|---|---|
| A/B | Oils for gasoline and light diesel engines | Passenger cars |
| C | Eco-friendly oils for engines with catalysts | With particulate filter |
| E | Oils for heavy diesel engines | Trucks |
| ACEA A5/B5 | Energy saving oils with low viscosity | Modern engines |
When choosing, be sure to check the instructions for your car. Using an oil of a lower grade than required may void the warranty and cause accelerated wear.
What is Low SAPS?
Low SAPS are oils with a reduced content of sulfated ash, phosphorus and sulfur. They are necessary for vehicles with diesel particulate filters (DPF) to prevent them from becoming clogged during combustion.
Specifics of diesel and gasoline engines
Although many modern oils are universal (labeled as API SN/CF), there are fundamental differences between lubricants for diesel and gasoline. Understanding these nuances will help you avoid fatal mistakes.
Diesel fuel burns at lower temperatures but produces more soot and sulfur compounds. Therefore, diesel oils must have high alkaline properties (TBN) to neutralize the acids produced by the combustion of sulfur. They also contain more detergent additives to combat carbon deposits.
Gasoline engines operate at higher speeds and temperatures. For them, oxidation resistance and the ability to prevent coking of piston rings are critical. Trying to pour pure diesel oil into a gasoline engine can lead to overheating and detonation.
- 🔹 Diesel oils have a high alkaline index to combat acids.
- 🔹 Gasoline oils are focused on protection against high-temperature deposits.
- 🔹 Universal oils are suitable for both types, but with limited resources.
If you own a car with a Common Rail system or pump injectors, you absolutely cannot save on oil. The precision of processing friction pairs in such systems reaches microns, and any particle of dirt or loss of lubricating properties leads to expensive repairs.
⚠️ Attention: Using oils for old diesel engines (API CD, CE) in modern engines with catalysts is guaranteed to damage them within a few thousand kilometers.
Automaker approvals: what to look for
The most accurate guideline when choosing is the approvals of car manufacturers. Large concerns (VAG, BMW, Mercedes, Ford) conduct their own oil tests and issue certificates of compliance with their standards. Having the right approval on the canister is more important than the general API or ACEA classifications.
For example, for Volkswagen group cars, tolerances are important VW 502.00 (for gasoline) and VW 505.00 (for diesel). Specifications relevant for BMW BMW Longlife-01 or BMW Longlife-04. Mercedes requires compliance with standards MB 229.5 or MB 229.51.
It is best to start searching for the right product not from the store shelf, but from the technical documentation for the car or specialized online selection services. Enter your VIN code and get a list of recommended products.
☑️ Check before purchase
Remember that approval is the result of expensive testing. The oil manufacturer confirms that its product has passed the burnout, rubber compatibility and wear protection tests specifically for this engine.
Synthetics versus mineral water: myths and reality
There are many legends surrounding the types of oils. One of the most popular says that if mineral water has been poured into the engine, then it is no longer possible to switch to synthetics - “the seals will crumble.” This statement is only partially true and applies only to very old, worn-out engines.
The real problem lies in the cleaning properties of synthetics. If a layer of sludge and deposits has accumulated in an engine that runs on mineral water, aggressive synthetics can dissolve it. A suspension of dirt will enter the oil receiver and cause oil starvation. Therefore, an engine flush is often recommended before switching.
On the other hand, for modern engines designed for synthetics, the use of mineral oil is unacceptable. The gaps in such motors are minimal, and thick mineral water simply cannot penetrate all lubrication units, especially during a cold start.
- 🔸 Myth: Synthetics always cause leaks. Reality: It just flushes dirt out of old seals.
- 🔸 Myth: Mineral water is better for old engines. Reality: Yes, if the engine is worn out and has leaks, viscous mineral water can temporarily reduce the waste.
- 🔸 Fact: Synthetics last longer and better protect against liner rotation.
The main selection criterion is not the price or type of base, but compliance with the tolerances of your car manufacturer specified in the service book.
It is also important to consider replacement intervals. Even the most expensive synthetic oil loses its properties after 10-15 thousand kilometers, especially in city traffic jams. In the city, engine hours accumulate faster than kilometers, so you need to change the oil more often than scheduled.
Is it possible to mix oils from different brands?
Technically, mixing oils of the same viscosity class and base is possible in emergency cases (up to 10-15% of the volume) in order to get to the service station. However, long-term operation with a “cocktail” is not recommended, since the chemical composition of additives from different manufacturers may conflict.
How often should you change your oil?
The standard interval of 15,000 km is relevant for ideal route conditions. In a real city with traffic jams and cold starts, it is recommended to change the oil every 7,000 - 8,000 km or 250 engine hours.
Does the color of the oil affect its properties?
No. The color of the base oil depends on the degree of purification of the oil and the dyes used. Black oil in an engine is often a sign of good cleaning properties, as it keeps combustion products in suspension, preventing them from settling on parts.