Top up engine oil

Engine oil is nothing more than a wearing part. The amount of oil decreases steadily depending on the operating time. This is due to thermal and mechanical effects. The oil evaporates through heat, decomposes through oxidation or ages through wear of the additives.

Refilling a car engine with motor oil
Every car needs the right engine oil to make the most of its performance

When should you measure the oil level?

To ensure that the engine is properly lubricated, it is advisable to check the oil level regularly. It is recommended to check every 1,000 kilometres. You should react immediately when the engine light of your car flashes yellow. If the oil level is actually too low, top up the required amount of engine oil that has already been filled. We do not recommend mixing different oils as described above. If you do not change the oil yourself, always ask your trusted workshop for the oil that has been refilled. Of course, you can also specify which engine oil is to be used.

Oil dipsticks with different oil levels
Representation of an oil dipstick with different filling levels: Empty (left), oil level low (2nd from left), oil level normal (2nd from right), oil level too high (right)

What has to be considered when refilling the engine oil?

Only measure the oil level when the engine is warm and at operating temperature. Make sure that the vehicle is straight and has not been parked on a slope. After switching off the engine, it should take about five minutes before the measurement is taken. This can cause the still warm oil to settle in the oil pan.

Then open the bonnet and pull out the dipstick. Usually the dipstick can be identified by a yellow ring. Wipe the dipstick with a cloth and reinsert it into the engine block. In the best case, the oil level should now be between the two marks (see picture above). Then the oil level in the engine is optimal. If there is too much oil in the engine, you must drain it, dispose of it and check for oil dilution (see next section). If there is too little oil in the engine, you should top up with engine oil.

When refilling, proceed slowly and add only small quantities. Test the level regularly until the desired result is achieved. This will prevent the motor from overfilling. If the engine oil level is too high, engine damage may occur. Foaming of the engine oil can occur, which impairs the lubricating effect.

Someone fills motor oil in a motorcycle
If the oil level is too low, top up with oil

Oil dilution - engine oil smells like petrol

When measuring the oil level, it can happen that the oil has a smell of petrol. This only occurs when petrol mixes with engine oil and so-called oil dilution occurs. Oil dilution is an undesirable effect that occurs primarily in petrol engines, but diesel engines are also affected. During a cold start, fuel settles on the cylinder walls and is introduced into the oil via the piston ring. There is a mixture of oil and fuel. Since the oil in the engine usually assumes a temperature of 80-100 °C, the fuel is not completely burned. Parts of the fuel remain in the lubricant and continue to dilute it. This can cause the oil level to rise slowly.

How can oil dilution be avoided?

The effect is intensified by driving mainly short distances, especially at cold outside temperatures. The engine is often started cold and rarely reaches the optimum operating temperature. This accumulates a lot of fuel in the oil. So if you have to drive many short distances, it is always advisable to move the vehicle over longer distances and to drive faster. Then the residues of the fuel can burn better. This is because too much fuel in the oil leads to inadequate lubrication. The viscosity of the oil changes and the optimum oil pressure can no longer be built up. In the worst case, the result is engine damage.

Another reason for oil dilution may be a defective thermostat in the radiator. If this cools the engine down too much, too much fuel is also deposited on the cylinder walls.


Sven Köhler

Product Manager Automotives / Gas Engine Oils