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The mixability of modern motor oils with one another, regardless of the type, must be possible under any circumstances. For it is not always guaranteed that the average car driver will know which motor oil was used by the garage in an oil change.

No! You can, of course, always use the matching LIQUI MOLY product.

You do not need to be an expert to add more motor oil to a vehicle. Yet there are a few important things to bear in mind:

    ■Before the motor oil can be added to, the precise oil level has to be established. This takes place using the dip stick (mostly identified by color in the area of the oil filler neck). The vehicle must be on an even surface. To measure, simply pull out the dip stick, wipe off any oil, put it back in and pull it out again. Now the precise oil level can be read and, if necessary, easily corrected.

    ■On the dip stick, there is generally a liter between the marks of MIN. and MAX.

    ■The right oil has to be used. If this is not known, our Oil Guide or our technical support by phone +49 731 1420-871 can help



The oil level of the motor must always be correct, as both too little and too much oil can lead to serious damage of the motor. If you add too much oil, this can lead to the creation of many air bubbles. These air bubbles are then sucked by the oil pump and moved through the motor to the lubrication points. As air famously does not lubricate, greater wear is generated at the areas of friction to be lubricated, which can lead to motor damage.

A further problem of overfilling is increased oil pressure. This can lead to seals, which are supposed to keep the oil in the motor, being torn from their actual position or damaged and therefore the motor becoming leaky.


The acronym API stands for American Petroleum Institute. It sets the global quality requirements and testing criteria of lubricants, such as motor or gearbox oil.

The question of which motor oil is suitable for diesel motors keeps coming up, again and again. But the times in which there were special motor oils for diesel motors are long gone. Modern motor oils fulfill both the requirements of petrol and diesel motors. What's important in the selection of the right motor oil is much more the specification or approval given by the vehicle manufacturer. If this is printed on the bottle label, then the oil can be used for the respective motor. Regardless of whether it's diesel or petrol.

If a vehicle is mainly used for short journeys, this has the consequence that the condensation created by temperature differences mixes with the oil and does not evaporate. This oil/water emulsion is then deposited in the entire motor. This becomes visible at the oil filler cap in the form of light-brown sludge. In order to free the motor of this, LIQUI MOLY offers the oil sludge purge.

The color of a motor oil provides no conclusions regarding quality or age. There are, therefore, chemical additives that superimpose on the actual color (amber) of the oil and therefore make it appear darker.

There is no general answer to how often a motor oil has to be refilled. Oil consumption can vary greatly even with motors identical in construction. If there is no oil level control fitted, the oil level should be checked every time you refuel and correspondingly reacted to.

What's important in the selection of the right motor oil is the specification or approval given by the vehicle manufacturer, which can be found in the operating manual of the vehicle. If this is printed on the label of an oil, then this oil can be used for the respective motor. If you are not sure about this, our Oil Guide or our technical support by phone +49 731 1420-871 can help.

The fill level of the motor oil is always measured when it is warm. This ensures that the motor is in the temperature range in which it usually is, optimally supplied with lubricant.

Fundamentally, the recommendation of the manufacturer should be followed when selecting the oil for snow blowers. However, experience shows that our Special Tec LL 5W-30 covers the majority of snow blowers available on the market.

We keep receiving questions like "what do you think of a motor oil change after as long as two years?". Without a sound laboratory analysis of the old oil, the car driver cannot assess the condition of a motor oil by the color or by rubbing it between their thumb and index finger. When a change of the lubricant is necessary is decided either by the vehicle itself (variable) or the change was set by the manufacturer according to a fixed mileage or age. In the case of a variable change interval, the vehicle will tell you when a change is required. The mileage until the next change can simply be called up in the vehicle menu. Should a change be prescribed, the date is usually written on the oil note in the motor compartment or in the service booklet of the vehicle.

A definite yes! Modern motors are highly complex mechanical assemblies. Due to the high requirements expected of them they require a lubricant aligned to the materials and properties. If it does not receive this, the increased friction may lead to motor damage.

As there are soot deposits in the oil circuit particularly in diesel motors, but also in petrol motors, the oil is often colored black after the first few revolutions of the motor. However, this is no reason to panic, as the oil is doing what it should: It is cleaning! While doing so, it is absorbing the soot deposits in the motor and then transporting it to the oil filter.

The minimum durability in small containers is five years – assuming it is stored in a dry place at temperatures between + 5 °C and + 30 °C and is not in direct sunlight. The cellar, and not the garage, is ideally suited to storage.

Fundamentally, the specifications of the gas system manufacturer and the motor manufacturer should be observed. If the vehicle manufacturer approves more general specifications (e.g. ACEA C2/C3 or C4), then low ash oils according to this specification are to be preferred during gas operation. Furthermore, Cera Tec as an oil additive for gas-operated motors is of a fundamental advantage. A dose of 7% to 8% in the motor oil is optimum.

Two-stroke oil dissolves fully in fuel and does not become separated even after an extended storage period.

What is decisive for the selection of an oil is the quality and the manufacturer guidelines, not the viscosity. This information can be found on the container label. The 5W-30 specification relates only to the liquid condition of an oil at a certain temperature and is not a sign of quality.

Yes! The mixability of the motor oils with one another must be possible in order to guarantee refilling at any time. However – depending on the oil added – the quality or the properties of the existing oil are changed.

Motor oil has molybdenum disulfide added to it. This anthracite-colored additive superimposes on the "normal" color of the oil.