The choice of motor oil lubricant on your car engine is essential as it largely affects its performance. A car engine that’s lubricated with the best grade of oil is more efficient as its functioning parts work more smoothly. Engine power shouldn’t be wasted in overcoming friction and also you get a better mileage out of your car.
Motor Oil Viscosity Explained
Viscosity is the property of every fluid which decides how smoothly and simply it will flow and the way much resistance will it offer to its own flow. Thinner and low-viscosity fluids move faster and more smoothly than thicker, high-viscosity fluids. For example honey, as a result of its high viscosity moves slower than water which has lower viscosity.
It relies on the interior properties of a fluid, including its chemical composition and temperature. With higher temperature, viscosity of most petroleum-based oils decreases they usually thin out. So, viscosity of motor oil, being a function of temperature, is never specified without the actual value of temperature, at which it is supposed to supply best lubrication service.
A car engine’s moving parts are constantly bathed in oil which forms a skinny film on their surface to forestall friction. Another function served by the oil is that it effectively suspends the small contaminants that could cause friction and makes sure that they don’t come in contact with moving parts. To take care of consistent lubrication levels, the viscosity must be stable over a spread of operating temperatures.
The car engine’s temperature is never constant. It changes during operation of the engine and likewise changes with the encircling temperature. With lowering of temperature, the oil becomes sluggish as its viscosity increases and its lubrication function is less efficiently executed. At high temperatures, during high RPM operation, the engine oil can thin out as a result of lowering of viscosity and its lubrication film also thins out.
A single grade motor oil is designed to perform efficiently and hold a particular viscosity, just for a certain temperature range. That is why, when temperature changes drastically, a single grade oil’s vulnerability is exposed.
In car manufacturer’s lingo, viscosity of oil is also known as weight. Today, multi-grade or multi-weight engine oils have been developed which might withstand high, as well as low temperatures. That is made possible by the polymer additives in these oils that prevent thinning up of the oil at high temperatures and thickening at low temperatures.
The viscosity of an oil type is decided by the ‘Society Of Automotive Engineers (SAE)’ and graded by an SAE number. The number decides how fast or how sluggishly oil flows under specified temperature conditions.
The higher the SAE number, higher would be the viscosity of the oil used. For instance, SAE 20 is less viscous than SAE 60. There are special ‘Winter Grade’ oils that maintain a low viscosity, even at low temperatures. Multi-grade oils are specified with dual SAE numbers and with a ‘W’ in between that specifies its winter grade nature. So if a motor oil has a SAE number of 10 W-30, that means it shows a viscosity of 10 at low temperatures that occur in winter, while the second number- ’30’ signifies the upper viscosity it demonstrates at high temperatures.
How to decide on the best Oil?
Every car engine is exclusive and the choice of motor oil for it, is set by the weather conditions in which it is used. Your car maintenance manual specifies the viscosity value that can be right to your car model. So, open the manual to know its required grade of oil.
Manufacturers provide viscosity charts that may be referred to while buying. Should you shouldn’t have a car manual, then a general rule to follow is, go for top SAE number oils in case you are using your car in colder weathers and a low SAE number motor oil if you live in temperate regions. However, it is best to search out out the recommended specifications to your car model and go ahead accordingly.
In summary, viscosity decides how well your engine will perform under varying temperature conditions. Periodic changes of oil are necessary because of the creation of sludge, which is created by suspension of contaminant particles in it. Check with your owner’s manual for recommended oil change timing.