Everyone knows that an engine needs oil to run and that it needs to be changed regularly, but why? Here's what you always wanted to know about engine oil.
What Exactly Does Engine Oil Do?
Whether it's the engine on your vehicle, motorcycle, outboard motor, or lawnmower, the engine needs oil to run properly. An engine is made up of a bunch of different parts, almost always fabricated from metal. Because of combustion, which means the process of burning something, these parts also get very hot. The engine and its related parts need to be lubricated. This protects the metal from the enormous heat. It also reduces friction between the extra moving parts.
The oil also incorporates the by-products of combustion. Because it is a viscous substance, the oil absorbs the carbon and other components that are produced from the combustion process. This soot is why new oil starts out amber colored, but slowly becomes black overtime.
What Do The Letters And Numbers Mean?
The thing that makes motor oil able to keep the moving parts lubricated is its viscosity. This word means a measure of its resistance to tensile stress, but to simply it further, it basically boils down to how thick it is. Water has a much lower viscosity than molasses or maple syrup does, for example. A substance like water wouldn't get the job done. The bigger the number, the higher the viscosity and the more resistant to flowing the substance is. Since water has a low viscosity, it flows very easily, whereas molasses has a high viscosity and is "as slow as molasses" when it comes to flowing.
The Society of Automotive Engineers (SAE) rates oil viscosity from 5 to 50. So in the case of the common motor oil SAE 10 W 30, the first number is the viscosity of the oil at a low operating temperature. This means a SAE 10 W 30 is good in places where the coldest weather is -10 degrees Fahrenheit. In the case of SAE 5 W 30, it is good for even colder places, -25 degrees Fahrenheit. The "W" stands for winter as the viscosity of a substance obviously changes when it is colder. Cold honey is going to flow slower than warm honey, right? The second number in both formulations, 30, indicates how the oil will flow when it is hot. So essentially, the only difference between the two is a SAE 5 W 30 will perform a little better in cooler climates, but they will both perform the same at normal operating temperatures.
Contact a company, like Small & Sons Oil Dist Co, for more help.