Vehicle manufacturers are responsible for establishing the most adequate viscosity for their different models, which is included in their manuals. Usually, several viscosities are recommended since it may be necessary to adapt the viscosity to the vehicle’s usage conditions and the weather conditions.
It is not advisable to mix lubricants with different viscosity levels.
Mixing oils with different viscosity indexes can have negative consequences for your vehicle’s engine. The viscosity index is a measure of the oil’s capacity to maintain its viscosity at different temperatures. If you mix oils with different viscosity indexes, it can alter the oil’s capacity to maintain an appropriate viscosity in different temperature conditions and cause lubrication problems.
To improve the flow of the lubricant in cold temperatures and thus reduce friction losses and fuel consumption. The lubricant must be sufficiently fluid to be pumped easily and facilitate starting the engine during start-up.
The viscosity index is a measure that represents the variation of viscosity with the temperature. Generally speaking, the higher it is, the lower the variation of the viscosity, which is better for the operation of the equipment.
The SAE (Society of Automotive Engineers) has established an internationally accepted standard based on the differentiation of viscosity at different temperatures.
This classification defines a series of grades for engine oils and contains two subclassifications: one designated by a “W” which refers to the properties of the oil at low temperatures, and another without “W” which refers to the properties at high temperatures.
Therefore, oils designated with a numerical grade followed by the letter W (such as SAE 10W) or simply with a number (such as SAE40) are called monograde oils. On the contrary, those which are designated by the two types of grade (such as SAE 10W-40) are called multigrade because they are capable of simultaneously bringing together viscosymetrical properties at both low and high temperatures.
Viscosity is the resistance of a liquid to flow and, in the case of lubricants, it is an essential characteristic to take into account when choosing which is the best product for you.
Vehicle manufacturers are responsible for establishing the most adequate viscosity for their different models, which is included in their manuals. Usually, several viscosities are recommended since it may be necessary to adapt the viscosity to the vehicle’s usage conditions and the weather conditions.
Viscosity is not indicative of the quality or suitability of the oil, it is just one of the properties to take into account when choosing a lubricant. However, quality level is what sets one lubricant’s properties apart from another. These quality levels are usually indicated on the label.
It is not advisable to mix lubricants with different viscosity levels. You should only do this when really necessary such as refilling when the oil level is low. You should use an oil with the same quality level as the one used in the vehicle and, if possible, from the same manufacturer.
Lubricants can be classified according to their state:
- Liquid: lubricating oils which represent the majority,
- semi-solid: would be greases,
- solid such as graphite,
- and even gas.
Another classification can be made according to its nature, referring to the base oil it contains. We distinguish between synthetic, semi-synthetic, and mineral oils.
When the base oil is obtained through the conventional refining of petroleum, it is considered mineral. When it is obtained through more complex processes (chemical synthesis or other), the lubricant is considered synthetic. A semi-synthetic lubricant would be the combination of mineral and synthetic base oils.
You would have to check if this change is allowed by the manufacturer.
