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 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.
These tasks lead to a certain amount of oil consumption. Thus, the expectation that further development of the combustion engine will eventually mean that engines will not consume any oil is wrong.
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 rpm above idle speed are the main causes of oil dilution.
As oil consumption does not stabilise until after a few thousand kilometres of travel, oil consumption measurements are not reliable until after a distance of about 7,500 km.
Before measuring consumption, ensure that the engine is not losing oil due to leakage.
The oil dipstick can only be used to check oil level. It cannot be used for measurement. The engine must have been off at least 5 minutes before checking oil level. If after an engine oil change the maximum oil capacity does not match the maximum level of the dipstick, this is due to necessary manufacturing tolerances.
All information on permissible engine oil consumption and capacities are found in the Owner's Manual.
- 1. The check is carried out with the vehicle parked on a level surface with the engine at operating temperature (engine oil temperature at least 80°C).
- 2. Drain the engine oil immediately after switching off the engine; drainage time = approximately 30 minutes (this value has been obtain through technical trials).
- 3. The quantity of drained engine oil is determined via a measuring container. The container is then filled with fresh oil up to the maximum engine oil capacity minus the volume remaining in the unchanged oil filter.
- 4. With this engine oil quantity, the customer should be able to travel 1000 km without needing to top up the engine oil (the distance profile and customer driving style should be maintained).
- 5. Then, the preceding procedure (points 1 and 2) should be repeated with the exact same engine drainage time.
- 6. The oil quantity now "missing" from the measuring container is equal to the engine oil consumption for that distance.
- 7. Oil consumption is calculated as follows: Fill oil quantity (l) - Drained oil quantity (l) x 1000 = Oil consumption (l/1000 km) Total distance driven (km) Approximate Oil Fill Capacities Engine Oil pan (l) Oil filter (l) Other (l) Total (l) K10B 2.8 0.2 0.2 3.2 K12B 3.2 0.2 0.3 3.7 D13A — 0.1 — 3.2 Z13DTJ — 0.1 — 3.2