The main difference between full synthetic oil and semi-synthetic oil is that the semi-synthetic oils contain a smaller proportion of refined oil, and are a mixture of synthetic oil and mineral oil.
Semi-synthetic oils are made up of base oils, which consist mostly of mineral oil and full synthetic oil in carefully selected proportions, and include additives.
This allows the properties of the motor oil to be adjusted somewhat. The properties of semi-synthetic oil can be adapted more than mineral oils, but not as much as full synthetic oil.
Mixing different motor oils
Modern motor oils such as full synthetic, semi-synthetic, and mineral oils can normally be mixed with each other, regardless of type. But be aware that each type of oil has its own additive that gives it specific properties, and these properties can change when mixed. Therefore, it is always preferable to do an oil service and ask your workshop which motor oil was used during the oil change.
Before you buy new motor oil, you should check what your car’s manufacturer recommends. This information can be found in the car’s physical or digital manual. Among other things, the manual will state the oil type and viscosity grade you should use and which specifications the oil should conform to.
If you are unsure, we advise you to talk to your workshop or a member of staff in our stores.
Frequently asked questions about semi-synthetic oils
What do the numbers and the W stand for?
The viscosity of an oil is measured by its flow resistance. There are two numbers that define the viscosity of an oil. The number ending with the letter W (winter) relates to how an oil flows when it is cold, like when starting the engine. The second number describes how an oil flows at the engine’s normal operating temperatures.
Which oil is thickest, 5W-30 or 10W-40?
The lower the number, the easier it will flow. So 5W-30 flows more easily than 10W-40 at lower temperatures, like when starting the engine. And a 10W-30 flows more easily than 10W-40 at the normal operating temperature of the engine. Oils naturally thicken when it gets colder and become more fluid at higher temperatures.
Which viscosity is best?
You should always check your car’s manual to find out which viscosity grade is suitable for your car. Thin viscosity oils protect engine parts at lower temperatures, and thick high viscosity oils protect the engine more effectively at higher temperatures.
