In the following content and tutorials we will learn more about oils/lubricants, so that you can make better choices when selecting a lubricant for your rotating equipment. The following will assist you in your journey to extend equipment life and identify the causes of bearing failure and eliminate them through applied lubricant knowledge and practices.
Below is a series of lubrication Q&A along with some practical examples.
Firstly and most importantly Viscosity is the most important property of the lubricant and forms the first line of protection in minimizing equipment wear and failures. 
So let's begin... 
Q: What is viscosity and why is it important?
A: Viscosity is the measure of a liquids resistance to flow,...now why is that important? It's important because the primary function of a lubricant is to keep surfaces from coming into contact with one another. In engines or equipment an oil achieves this through its viscosity depending on the speed and load and temperature...
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Q: What is a Viscosity Index and when is it important?
A: Viscosity Index can be described as the rate by which viscosity changes with the change in temperature. Viscosity index is important when you are operating at high or very low temperatures. High Viscosity Index lubricants are also important when you are operating over a very wide temperature range. i.e. a pump which starts up at very cold temperatures but the process material being pumped is at a very high temperature resulting in the lubricating oil going from a very low temperature to a very high temperature.
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Q: What is "Flash Point" and why and when is it important?
A: Firstly, what exactly is Flash Point? Flash point is defined as the temperature at which the vapours of a substance ignite, when exposed to an ignition source, therefore flash point serves as a valuable tool in determining product safety, the higher the flash point of an oil the safer the product is from a fire safety perspective. The Flash Point however can also give you clues as to the composition of a lubricating oil.
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Q: What is "Pour Point", why and when is it important?
A: Pour Point is defined as the lowest temperature at which a liquid is still fluid enough to pour, therefore pour point serves as a valuable tool in determining cold temperature performance. The lower the pour point the better the cold temperature fluidity of a lubricant which allows it to form a good fluid film even at extremely low temperatures, as low as -70°C. A very low pour point allows for easy equipment startup without requiring external heating which again requires more energy etc. 
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Q: What are "Copper Corrosion" values and when to worry about them?
A: A "Copper Corrosion" value is a series of numbers and letters (1A, 1B, 2A, 2B and so on) allocated to a lubricant which allows us to identify how much free Sulphur or active Sulphur is present. The more free Sulphur is present in the oil, the greater it's EP (Extreme Pressure) performance is. This free Sulphur forms a sacrificial layer on metal surfaces and protects the metal underneath. It however does have its drawback and shouldn't be used in yellow metal applications due to corrosion.
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Q: What is the "Rust Test" and why is it useful?
A: A "Rust Test" is important because it gives you an indication as to the level of protection you could expect from not only Rust but also salt water corrosion.