Type of Engine Oil
The most commonly used engine oils for diesel semi-trucks are:
- SAE 15W-40: This is a multi-grade oil suitable for a wide range of operating temperatures. It provides good protection against wear and tear, and is commonly used in older diesel engines.
- SAE 5W-40: This multi-grade oil offers better low-temperature performance compared to SAE 15W-40. It is suitable for use in both cold and warm climates, and is recommended for newer diesel engines.
- SAE 10W-30: This multi-grade oil is commonly used in newer diesel engines that operate in moderate climate conditions. It offers improved fuel efficiency compared to SAE 15W-40 and SAE 5W-40.
Oil Viscosity
The viscosity of engine oil refers to its thickness or resistance to flow. Diesel engines generally require higher viscosity oils compared to gasoline engines due to the higher stresses and temperatures they experience.
The SAE (Society of Automotive Engineers) viscosity grade of an oil indicates its viscosity characteristics. The lower the number before the "W" (winter), the better the oil's low-temperature flow properties. The higher the number after the "W," the higher the oil's high-temperature viscosity.
For example, SAE 15W-40 has a lower cold-temperature flow rating compared to SAE 5W-40.
API Service Categories
In addition to viscosity, it's important to consider the API (American Petroleum Institute) service category when selecting engine oil for a diesel semi-truck. The API service category indicates the oil's performance characteristics and its compatibility with certain engine types and technologies.
Common API service categories for diesel semi-truck engine oils include:
- API CI-4: This category covers heavy-duty diesel engines with four-stroke cycles.
- API CJ-4: This category covers heavy-duty diesel engines with four-stroke cycles manufactured after October 1, 2006. It provides better oxidation stability and high-temperature performance compared to API CI-4.
- API CK-4: This category covers heavy-duty diesel engines with four-stroke cycles manufactured after December 31, 2016. It offers reduced emissions, improved fuel efficiency, and better low-temperature performance compared to API CJ-4.
It's important to refer to the manufacturer's recommendations when choosing the appropriate engine oil for your diesel semi-truck. The recommended oil viscosity and API service category can typically be found in the truck's owner's manual.
