Engine oil is a lubricating fluid designed to reduce friction and wear between moving parts inside an internal combustion engine, while also cooling, cleaning, and protecting components from corrosion and deposits.
While we may think that there are numerous car manufacturers globally, as of 2025, there are only slightly over 100 original equipment manufacturers (OEMs), but over 5,000 models. Whether it’s a luxury vehicle or a basic, functional one, they all require one thing to keep them running: lubricants (in the EV market, this can mean greases as opposed to traditional oils).
Parallel to the various models of vehicles, there are also numerous types of lubricants on the market, each designed specifically for different requirements. In this article, we will share some knowledge on the areas you need to be familiar with for these types of lubricants, and of course, what impacts they have on your vehicle of choice.
Understanding Viscosity and Engine Oil Grades
Before exploring the types of oils, it is essential to understand one of the most important characteristics of oil: its viscosity. This is what governs the engine’s functionality and, to some extent, dictates its performance.
What is Viscosity?
Oil viscosity is the internal friction within an oil that resists its flow. It measures the oil’s resistance to flow and is one of the most important factors in lubricants. Viscosity is also defined as the ratio of shear stress (pressure) to shear rate (flow rate).
The SAE Viscosity Rating System
The SAE (Society of Automotive Engineers) developed viscosity grades to classify engine oils, enabling engine manufacturers and oil marketers to make recommendations and label their products accordingly. The SAE J300 is a series of two viscosity grades: one with the W and one without the W.
Monogrades with the letter “W” are defined by maximum low-temperature cranking and pumping viscosities and a minimum kinematic viscosity at 100°C. (Typically, this represents the start-up condition of an engine.)
Monogrades without the W are based on a set of minimum and maximum kinematic viscosities at 100°C and a minimum high temperature / high shear measured at 150°C and 1 million reciprocal seconds (s-1). (Typically, this represents the operating conditions of the engine when it is in use.)
Multiple viscosity grade oils or multigrades are defined by:
- Maximum low-temperature cranking and pumping viscosities
- A kinematic viscosity at 100°C that falls within the prescribed range of one of the non-W grade classifications
- A minimum high temperature / high shear viscosity at 150°C and 1 million reciprocal seconds (s-1).
These represent the extremes of startup and engine operation.
The table below gives a summary of these.
