Information On Engine Oil Consumption
Information:
Causes of engine oil consumption
Every combustion engine uses a normal, system-conditioned amount of lubricating oil. Engine oil is mainly used in the following areas:
- Pistons with piston rings (interaction with cylinder liners)/valve-stem seals in the cylinder head (lubricating oil used in the valve guide)
Minute amounts of engine oil stick to the cylinder walls during each piston stroke. Some of the engine oil is used during combustion and is expelled together with exhaust gases. The effect increases as engine speed increases. For this reason, high-speed engines and turbocharged engines tend to use more engine oil than low-speed engines.
- Positive crankcase ventilation
Positive crankcase ventilation carries oil spray (thoroughly atomised fuel) and feeds combustion air back in again. Here, the oil spray passes the oil separator, the main function of which is to filter the oil from the blow-by gases. Oil separation systems work best at a defined gas volume. Oil consumption can increase if the volume is different.
- Turbocharger status
Engine oil is supplied to the turbocharger's turbine shaft while the engine is running. During operation, varying amounts of oil get into the combustion gases, depending on the turbocharger status and the driver profile.
Causes of increased engine oil consumption
Complaints relating to excessively high oil consumption can generally be attributed to the following causes:
- Customer's subjective opinion:
The customer's gut feeling is telling him/her that the oil consumption is too high, but the vehicle's actual oil consumption corresponds to technical requirements.
Porsche AG confirms that engine oil consumption of up to 0.8 l per 1, 000 km (US: up to 0.53 qt per 620 mls; UK: up to 0.44 qt per 620 mls) under normal conditions does not indicate a technical fault .
It is important to bear in mind here that new vehicles use more oil in the first 10, 000 km (6, 200 miles) than vehicles with engines that have already been run in as the components are "run in" during the first 10, 000 kilometres/6, 200 miles (even in modern engines). After 10, 000 km/6, 200 miles, oil consumption should level off to a lower level.
Other causes of increased engine oil consumption include:
- Sporty driving
- Frequent cold starts and frequent short journeys
- High engine load when pulling a trailer, long motorway journeys or driving over high mountain passes
- Poor fuel quality
- Technical fault, which results in increased oil consumption or oil loss:
The customer notices that the oil consumption or oil loss is too high and this is caused by a technical fault on the engine or peripheral equipment.
If the customer continually finds that (even on a vehicle with a mileage of more than 10, 000 km/6, 200 miles) oil consumption is more than 0.8 litres per 1, 000 km (US: more than 0.84 qt per 620 mls; UK: more than 0.7 qt per 620 mls), the Porsche partner should examine the vehicle again.
- Technical fault with the oil level display/oil level warning
If the driver sees a warning indicating that the oil level is too low despite having sufficient oil in the engine, this can be caused by a measurement error during oil level measurement or a system fault.
- Incorrect measurement: The system measures an excessively low oil level, which was influenced by the measurement environment (e.g. not waiting long enough after stopping the engine, inclined position of the vehicle, tyre inflation pressure is very different, vehicle's center of gravity is not consistent due to unbalanced load, etc.).
- System fault: The driver is incorrectly warned that the oil level is too low due to a hardware/software-related problem.
In the event of an incorrect measurement or system fault, it is not immediately possible for the customer to differentiate the difference from an actual 'low oil level' situation.