IF a liquid’s viscosity does not change much between these temperatures, it will have a higher VI and vice versa. This HT/HS test simulates an engine running under normal load conditions and measures in centistokes how well the oil maintains its viscosity over a given amount of time at a temperature of 150C (302F). This would be the “5W” in Amsoil XL 5W-30 Synthetic Motor Oil. The SAE defines high temperature oil viscosity at 212 degrees Fahrenheit (which is 100 degrees Celsius), which is the baseline used to approximate the operating temperatures of most vehicles. Meet Dan Parker, America's Fastest Blind Racer. Alternatively, there is dynamic viscosity, which is essentially the amount of energy required to move an object through the lubricant. The viscosity index is a unitless number, used to indicate the temperature dependence of an oil’s kinematic viscosity. This approach isn’t quite as colloquial as it may seem. There are several contributing factors that directly affect a given bearing clearance. This is where the “30” in 5W-30 synthetic oil comes from. However, when the weather is warmer, the oil becomes thinner and easier to circulate. You might have noticed that there are far more bottles of oil with a “W” on the label than there are with just a single SAE number. Engineering Explained and Mobil 1 demonstrate what different oil weights and viscosities really mean and how different viscosities effect your engine. Amsoil Inc. introduced the first full synthetic motor oil to meet American Petroleum Institute service requirements in 1972. Think of this like wearing a pair of snow shoes that allow you to walk on deep snow without sinking in. Speed’s test compared a synthetic Driven oil to a conventional Driven oil of the same viscosity and additive packages. Advertisement. Remove the shoes and your feet sink because your weight is concentrated on a smaller surface area. Additionally, you should be aware of what exactly the viscosity index (VI) is. These three are best considered together as opposed to individually since each affects the others in important ways. Engineering Explained and Mobil 1 demonstrate what different oil weights and viscosities really mean and how different viscosities effect your engine. Most engine builders we spoke to said they don’t make major clearance changes when building an aluminum block engine. How to Calculate and What it Means, How to Clearance Your Block for a Stroker Crankshaft. This number indicates the motor oils winter viscosity rating. As a generalized statement, 0.001-inch clearance offers a higher load carrying capacity than 0.002-inch using the standard 2.45-inch small-block main journal size as the example. The typical rule that most engine builders follow is that bearing clearance establishes the viscosity of the oil to use within a given oil temperature range. © 2020 EzineArticlesAll Rights Reserved Worldwide, Tips to Help You Buy the Best BMW Accessories and Spare Parts, How to Choose the Right Dashcam for Your Car, 5 Things to Consider When Choosing Engine Oil, 6 Things to Consider Before You Buy Your First Hoverboard. This can cause components in your engine to experience wear and tear. All multi viscosity oils will have two sets of numbers. For oil to offer the right protection and performance it has to ‘flow’ properly through and around the engine components. Common sense dictates that bearing clearance directly affects oil flow with predicable results. You might have noticed that there are far more bottles of oil with a “W” on the label than there are with just a single SAE number. Today Amsoil is considered the world leader in synthetic lubrication. Viscosity grades are similar. Moreover, thicker oil can increase internal operating temperatures, which can ultimately lead to engine failure as oil passages become blocked by sludge. The relationship between bearing clearance and oil viscosity is a delicate balance. So what 's the difference between say 5W/30 and 10W/30 motor oil? Additionally, you should understand what the numbers identifying different viscosities mean. Fortunately, Amsoil motor oil comes in a wide range of products to fit any vehicle. Additionally, an oil’s high-temperature viscosity grade is determined by its kinematic viscosity. Stay up to date by signing up for the Engine Builder newsletter. This leads directly to the value of film thickness, which is created by a combination of the oil viscosity, bearing speed, and load. So it may not be much of a stretch of the imagination for an engine guy to include the pairing of bearing clearances with oil viscosity as a duo you should become acquainted. Low-viscosity motor oil may be too thin, and can compromise the protection of your engine over time.