What functions does engine oil perform
Let's refresh a few well-known facts that, however, may not be familiar to everyone.
Lubrication of rubbing parts. The main task of oil is to minimize friction between contacting elements, thereby protecting the engine from premature wear. Thanks to the oil, a thin protective layer is formed between moving parts, which ensures reduced friction.
It should be noted that if the car has been sitting for some time, all the lubricant drains into the oil pan. Therefore, at the moment of engine start and for the first moments after, the engine is forced to operate without lubrication until the pump delivers oil throughout the system. It is during these seconds that the unit experiences maximum loads.
Additionally, on some cars with automatic transmission, the lubricant begins to circulate through the system only after the gear selector is moved to the "Drive" position. For this reason, warming up such cars is recommended to be done in this mode (details — in the owner's manual).
Heat removal. The cooling system with radiator and antifreeze certainly performs its task, but oil additionally absorbs heat by directly washing the contact zones of parts. To increase the efficiency of this process, some engine modifications are equipped with specialized oil coolers.
Anti-corrosion protection. The internal components of the engine operate in a rather aggressive environment: they are affected by high temperatures, their sharp fluctuations, as well as fuel combustion products. Special additives and supplements in the oil help prevent corrosion processes.
Strictly speaking, additives and supplements are not the same thing. Additives, mixing with the base oil, modify its characteristics, while supplements do not change existing properties but introduce new ones into the composition.
Removal of combustion and wear products. Deposits from fuel combustion (soot, carbon) and inevitable wear products of surfaces that rub against each other (metal shavings and dust) accumulate in the oil. All this dirt is removed from the system along with the draining of used oil.
What does oil "aging" mean
Over time, even in a fully functional engine, the lubricant inevitably ages: additives exhaust their service life, the oil oxidizes, and foreign contaminants accumulate in it. As a result, the oil gradually loses its ability to perform its key functions.
Sooner or later, the moment comes when the used lubricant must be drained along with all accumulated combustion products, spent additives, and other "engine waste," and a fresh portion must be poured in. During this procedure, one should not forget about replacing the oil filter — otherwise, the dirt accumulated in it will immediately enter the new oil.
What driving on old oil leads to:
- lubricating characteristics decrease — friction of parts increases, load on the engine increases, in advanced cases engine "knocking" is possible with the subsequent need for major repairs. In a less critical situation, one can expect a reduction in engine life, its overheating, and increased fuel consumption;
- heat removal deteriorates — which provokes even stronger overheating;
- protection against corrosion weakens;
- combustion and wear products settle inside the engine, clogging oil channels, which ultimately also threatens major repairs.
Oil change intervals
The scheduled oil change period is specified in the owner's manual of each specific car. Design engineers calculate this interval based on the characteristics of the specific engine and the intended conditions of its use. That is why recommendations on the type of oil, its change intervals, and maintenance frequency can differ significantly for different markets.
In Ukraine and Russia, service intervals and oil change frequency for most models are noticeably shorter than in European countries. And this is not always explained by the desire of service centers to earn money — rather, it is an objective recognition of the more severe operating conditions of cars in our latitudes.
Moreover, one should not rely on the approvals declared by oil manufacturers — in our realities they do not work. To ensure long and stable engine operation, oil should be changed no less frequently than prescribed by the car manufacturer.
The typical recommended change interval is 10 thousand kilometers of mileage. For a number of new models, the car manufacturer sets a service interval of 15 or even 20 thousand kilometers. This indicates the manufacturer's confidence in the reliability of its products, and for the owner it means direct savings on maintenance.
Nevertheless, a number of experts recommend adhering to an interval of exactly 10 thousand kilometers — more frequent oil changes have a positive effect on the engine's condition and will allow the car to serve faithfully longer, even after the warranty period ends.
If you are a little late with the change by 1-2 thousand kilometers, a catastrophe, of course, will not happen. However, the next change should be done 1-2 thousand kilometers earlier. But an overrun of 4-5 thousand kilometers already has an extremely detrimental effect on the engine's condition.
On synthetic oil, perhaps, you can drive extra thousands of kilometers (they say that some taxi drivers manage to drive 30-50 thousand without changing), but with every revolution of the crankshaft, the car inexorably approaches expensive major repairs.
Summary
The scheduled oil change intervals are specified in the car's owner's manual, and more frequent changes are exclusively beneficial for the engine.
A delay in changing by 1-2 thousand kilometers is undesirable but acceptable. An overrun of more than 4-5 thousand kilometers is extremely undesirable.
When purchasing a used car, it is reasonable to change the oil immediately.
Bottom line: what happens if you ignore oil change intervals? In an optimistic scenario — a deep flush with engine disassembly, in the worst case — its complete replacement.
