Vehicle owners are advised to refer to the manufacturer’s manual, where they can find the recommended vehicle engine oil. The SN or SM levels are the most advisable for the latest vehicles with gasoline engines, and the oil should always be multigrade, depending on the region where the vehicle is used. For earlier vehicles, the SL, SJ and SF levels were recommended, as there were no higher levels. In any case, the idea that «THE THICKER THE BETTER» is completely wrong. Always keep in mind that the manufacturer’s manual is the most reliable guide to check the recommended SAE Viscosity Grade and API Service Level for your vehicle.
The main function of engine oil is lubricating the internal moving parts of the engine in order to minimize wear and tear. Therefore, engine oil must have the
proper viscosity for cold starts to flow quickly to all points of the engine, just as it must have adequate viscosity at high operating temperatures, to guarantee lubrication. Other (but not less important) functions are the following:
- Cooling the engine internally.
- Controlling the formation of soot deposits, the product of combustion, to prevent the rings from the rings from becoming stuck in the ring grooves.
- Neutralizing the acids that are formed during combustion.
- Protecting against corrosion and rust.
Reducing wear and tear of engine internal components, thus cutting maintenance costs.
HOW ENGINE OILS ARE CLASSIFIED?
Internationally there are 2 classifications for engine oils, namely the SAE Viscosity Grade, which refers to viscosity, and the API Service Level category, which indicates whether the oil is for gasoline or diesel engines. Society of Automotive Engineers (SAE) Viscosity Grade: This refers to oil viscosity, regardless of the API level, and separates oils into two groups:
* Monograde oils: SAE 30, 40, 50
* Multigrade oils: SAE 10W30, 15W40, 20W50, etc.
Under the API Service Level category, oils suitable for gasoline are identified with the initial letter S, while oils suitable for diesel engines are identified with the initial letter C. For example: – Oils for automotive gasoline engines are divided into the following categories: SN, SM, SL, SH, SG…SN provides the highest performance level. – Oils for automotive diesel engines are divided into the following categories: CJ-4, CI-4, CH-4. CJ-4 provides the highest performance level. Additionally, according to the class of lubricant base used in their formulations, they can be classified as: mineral, semi-synthetic and synthetic oils. VENOCO formulates and produces the widest range of lubricants for each user’s specific needs.
WHAT IS THE MOST ADVISABLE AUTOMOTIVE ENGINE OIL:MONOGRADE OR MULTIGRADE OIL?
Because of false beliefs that the thicker the better an automotive engine oil, in most stores users are advised to buy monograde oils. Monograde oils are highly viscous at room temperature and quickly lose their viscosity when heated. On the contrary, multigrade oils have a low viscosity index at room temperature, and therefore they can be pumped more quickly into the engine during start-up, thus significantly reducing wear (about 60% compared to monograde oil). When temperature increases multigrade oils also lose their viscosity, but much less so than monograde oils.