Sealing effect

Sealing effect is one function of engine oil.
In engines, although the cylinder wall and compression rings are used to seal and compress the combustion chamber, engine oil is used to block the spaces between the cylinder wall and compression rings to complete the sealing effect and prevent the combustion gases from blowing through the crankcase.
By doing so, decreases in engine output and oil deterioration caused by unburned fuel are prevented.

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