Oil Consumption Diagnosis: Explanation

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NOTE:

Oil consumption for a combustion engine refers to the amount of oil consumed as a result of the combustion process. Oil consumption is not to be equated with oil loss resulting from leaks from components such as the oil pan and cylinder head cover.

The role of the engine oil is to:
1. Separate surfaces that slide against each other by means of an oil film, i.e. to prevent dry friction.
2. Dissipate heat generated by friction.
3. Lead away combustion residue.
This task involves the consumption of a certain amount of oil. It is therefore wrong to assume that future enhancements of the combustion engine may produce an engine which has zero oil consumption.
Outside operating conditions, driving style and manufacturing tolerances do, however, have an impact on oil consumption.
It is imperative that oil be filled when the level has fallen below the "MIN" mark on the dipstick.
It is also important to ensure that the oil level is not above the "MAX" mark on the dipstick as this could result in increased oil consumption.
As oil consumption is affected by technical factors, the conclusion is reached that the engine does not consume oil in special operating conditions that lead to oil dilution.
During conditions such as frequent cold starts and driving before the engine reaches operating temperature, it is only the oil flowing back to the oil pan that carries away scalding fuel components and precipitates. This "dilutes" the oil and leads to the erroneous assumption that the engine consumes no oil.
Such diluted oil loses its ability to lubricate and could cause engine damage if the prescribed oil change intervals are not observed.
Driving in predominately urban traffic and frequently running a cold engine at rpms above idle speed are the main causes of oil dilution.
As oil consumption does not stabilize until after a few thousand kilometers of travel, oil consumption measurements are not reliable until after a distance of about 7, 500 km.
The oil standard is merely used for monitoring and cannot be used for measurement purposes. In principle, the engine must have stopped for at least 5 minutes or 10 minutes before checking the oil level. If the maximum amount of oil added during an oil change does not agree with the max. on the oil dip stick, then this will be accounted for by the necessary manufacturing tolerances.