ENGINE OIL VISCOSITY SIMULATOR

The number before “W” is the low – temperature oil viscosity. SAE oils viscosity grades are in an “XW-XX” format, where “W” stands for Winter. These oils have two viscosity grades, so the same motor oil grade can be used yearly - and can perform at low, high, and normal engine operating temperatures. What Are Multigrade Oils?īefore multi grade oil blends were developed, most vehicles used one viscosity grade oil in the winter and another for summer.Īs motor oil technology evolved, additives like a Viscosity Index Improver (VII) allowed for multigrade oils. Oil viscosity grades for engine and transmission oils (SAE J300) were developed by the Society of Automotive Engineers (SAE). Here are the answers to some common oil viscosity questions: 1. Next, let’s explore some FAQs related to oil viscosity. Many refined conventional and synthetic oils have a viscosity index exceeding 100. If there’s little viscosity change in the test oil between 40☌ to 100✬, it will have a high viscosity index - meaning its viscosity is relatively stable with different temperatures. All three oils have the same viscosity at 100✬. One of the reference oils has a VI of 0, and the other has a VI of 100. It’s obtained by comparing a test oil’s kinematic viscosity at 40☌ with the kinematic viscosity of two reference oils. The oil viscosity Index (VI) is a unitless number representing how much the kinematic viscosity of a lubricant changes with temperature.

ENGINE OIL VISCOSITY SIMULATOR

It’s measured via the Cold Cranking Simulator test, which simulates engine startup at progressively lower temperature settings. Dynamic viscosity refers to the amount of energy required to move an object through a fluid.įor motor lubricants, dynamic viscosity determines the oil’s cold temperature viscosity grade (the “W” rating). You’d need more effort to stir the honey because it has a higher viscosity than water.

Let’s say you first use a straw to stir water, then honey. Dynamic Viscosity (Absolute Viscosity)ĭynamic viscosity (or absolute viscosity) is slightly different from kinematic viscosity. And this value is usually reported at either 40☌ (100☏) or 100☌ (212☏).įor motor oils, kinematic viscosity is usually measured at 100☌ as this is the temperature that the SAE engine oil classification refers to. The high-temperature viscosity grade of oils is determined by their kinematic viscosity (typically tested to ASTM D445). This is because water has a lower kinematic viscosity than honey. If you pour water into one container and pour honey into another, you’ll notice that water flows faster.

Kinematic viscosity is fluid resistance to flow and shear due to gravity. Another important viscosity indicator is the viscosity index. Oil thins out as it gets warmer, so engine oil viscosity refers to how well it pours at a particular temperature.Įngine lubricant viscosity is usually defined through its kinematic viscosity and dynamic viscosity (absolute viscosity).

Thick, heavy fluids have higher viscosity (like grease).

Thin, light fluids are low viscosity (like brake fluid).

Here’s an easy way to think of viscosity: It indicates how thin or thick a fluid is - impacting properties like temperature resistance and lubrication. Viscosity describes how resistant a fluid is to flow.

Engine oil viscosity