Why do I need to top up my oil between oil changes?
It’s normal for cars to burn a little oil as they age. The most common reason why an engine loses oil internally, the oil is slipping past the piston rings. All cars have it happen to some extent, especially when revving the engine at high RPMs.
This is usually older cars’ problem, where the piston rings are a little worn. It is not a big problem unless it is excessive. But it can also happen on some newer cars.
There are many different reasons for more oil being consumed by modern engines, here goes the list.
Today’s modern combustion engine is a super slim, lightweight marvel of engineering. The internal moving parts has been reduced “optimized” for the lightest possible to reduce fuel consumption, including the pistons’ size. The rings has been also slimmed down with low ring tension. This minimize friction, which result in more oil to be able to escape and get burned in the internal combustion engine.
Worth to note; the stoichiometric ratio, relatively speaking is fixed, which is 14.7 kg of air with 1kg of fuel provides the cleanest most effective combustion. This particular ratio cannot be changed too far in either direction, or the combustion becomes inefficient in the long term. This is why the engineers had to look for different solutions. This resulted in lighter more efficient internal components, including lighter weight motor oils.
Therefore lighter weight motor oils are chosen to reduce internal friction with minimized pumping losses and being lighter also easier to burn.
Definition of is stoichiometric ratio;
Combustion engines’ stoichiometric ratio (AFR) is the mass ratio of air to fuel present in a combustion process.
We could go further into the additional technical details, like running the crankcase ventilation under high vacuum to minimize reduce the pumping losses.
As you can see, there are multiple reasons for the oil consumption of a modern high tech internal combustion engine.
Last but not least the government legislated corporate fuel economy worldwide. This also having a serious effect on the design and manufacturing of today’s efficient internal combustion engines.
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