The question of what happens when mixing mineral and synthetic oils in an engine has been debated for many years. Some car enthusiasts are confident that such a mixture can seriously harm the power unit. Others believe that nothing terrible will happen, and the main thing is to use products from the same brand.
Let's try to find out whether such mixing is really dangerous for the engine.
What role does oil play in the engine?
As tests show, the engine can function without lubrication. However, this will not last long, and after such operation, the unit will most likely have to be written off. Engine oil performs a number of tasks:
- protects rubbing parts from wear and damage;
- minimizes power losses in overcoming friction;
- cleans the internal elements of the engine;
- removes excess heat from parts;
- dampens vibrations and noise, reduces shock loads.
In other words, it is the oil that ensures stable and long-lasting engine operation.
Key differences between "mineral water" and "synthetics"
Let us recall what these two types of engine oils consist of.
Mineral compositions are obtained during oil refining. Their characteristics are not stable, and evaporation is quite high. To improve performance, a significant amount of additives is introduced into them, which are destroyed over time. Therefore, mineral oil requires more frequent replacement.
Synthetic oils are created through chemical synthesis, and their parameters — such as viscosity, flash and pour points, base and acid numbers — are set at the production stage. These oils are stable, and thanks to good viscosity-temperature properties, they need fewer additives.
It is precisely because of stability and a smaller amount of additives that synthetics last longer and need to be changed less often. It also outperforms mineral oil in thermo-oxidative stability, evaporates less, and is not so prone to the formation of carbon deposits and sludge.
The difference between these oils is not only in the base stock. It also concerns the set and concentration of additives. Among them:
- thickeners;
- detergents;
- anti-wear additives;
- antioxidants;
- corrosion inhibitors;
- anti-foaming agents;
- friction modifiers;
- pour point depressants.
The compositions of additives differ not only between "mineral water" and "synthetics", but also between products from different manufacturers. This depends on many factors, including climatic operating conditions. It is the chemical composition of additives that plays a decisive role in how the engine will behave on a mixture of oils.
The main danger is in additives
If only base stocks interacted when mixing, the damage to the engine would be much less. The problem is that additives from mineral oil do not always dissolve in the synthetic base and vice versa. It is impossible to predict exactly what will happen when mixing specific oils. One thing is clear — the engine will suffer from such a mixture. First of all, due to the insoluble sediment that precipitates from the additives of the added oil.
This sediment can turn into a viscous substance and clog the oil pickup and channels. As a result, the engine will face oil starvation.
Operation in this mode, even for a short time, can lead to unit failure. It is important to remember: oil forms protective films and layers on parts. When other additives get into it, these layers are destroyed, accelerating part wear.
If mixing has already occurred
The main thing is not to panic. You should get to a service center as quickly as possible, without putting extra load on the engine. There, they will carry out diagnostics and decide whether a system flush is needed or whether it is enough to replace the oil and filter.
It is worth noting that a certain risk still exists. Sometimes mixing oils from the same manufacturer can pass without serious consequences, but only if such a mixture is used for a short time — for example, to get to a service station. But even in this case, a complete oil and filter change cannot be avoided.
