How often do I really need to change my oil?
Even with the best oil, after a while the additives are depleted and the oil becomes too dirty to function effectively.
Because of hot summers and cold winters in Kentucky, most drivers operate under severe conditions. Protech and Quaker State recommend using the severe service interval recommended in your owner’s manual for determining how often to perform an oil change. Also keep in mind, the time limit may come before the mileage limit.Your vehicle owner’s manual specifies the correct oil-change intervals for the car under normal and severe service conditions.Assume that your oil needs changing under the severe service conditions.
Quaker State Full Synthetic motor oil is your best weapon against engine wear. No leading synthetic motor oil provides better protection from friction-related wear than Quaker State.
Quaker State Full Synthetic Motor Oil provides
- Unsurpassed protection against friction-related wear, especially as temperatures increase in Kentucky.
- Improved resistance to engine stress at high RPMs and under heavy towing loads.
- Superior resistance to breakdown
- Superior lubrication at cold and high temperatures
- Exceeds the most stringent car manufacturer requirements for cleanliness and protection.
- If you want to keep your car longer, ask us about synthetics. The costs are actually the same as conventional oil changes. Ask us why!
What do all those numbers mean anyway?
Motor oils job is to protect your engine from wear caused by the friction created when moving parts rub against each other at high speeds and high temperatures. The quality that allows motor oil to lubricate those moving parts is viscosity, which describes the ability of a liquid to flow. In a laboratory, viscosity is usually assessed by measuring the flow of a liquid through a tube with an opening of a fixed size at a standard temperature, or by measuring the resistance that liquid exerts on a rotating shaft in a container. Bigger numbers mean greater resistance to flow and higher viscosity. Water, for example, has a very low viscosity and it flows quite easily. Molasses, which is thick, has a very high viscosity. Needless to say, neither one is a good bet as a substitute for motor oil.
Before we get to meaning of the numbers on a quart of oil, it is the high school topic where you were asleep in physics. Newtonian fluid dynamics. Typically for Newtonian fluids, lower temperature or higher pressure raises viscosity in a straight forward way as friction increases between molecules. In these liquids, more friction means greater viscosity (thickness), plain and simple.
But not all liquids behave in accordance with the dictates of Newtonian Viscosity. There is a class of fluids for which viscosity does not change in a straight line reaction to pressure or heat. These rebels of the liquid world are known as non-Newtonian fluids. In such liquids, for example, viscosity may decrease as temperature rises until a critical point is reached and then the liquid may suddenly become more viscous. Confused, hang in there.
What does this have to do with the numbers on a quart of oil, you ask? One of the tricks for making good motor oil is that its viscosity must be low enough so that it will flow when cool, but not so low that it fails to lubricate at high temperatures. In recent years, engineers have discovered that adding certain carbon polymers to petroleum lubricants will turn them into non-Newtonian fluids that are much better at protecting a car engine under a wide range of conditions. Those polymers are called viscosity modifiers, and motor oil makers have learned to add the just the right combination of viscosity modifiers to create lubricants that flow easily at very low temperatures while maintaining enough viscosity to lubricate the moving parts in an engine at very high temperatures.
So, those numbers on a quart of oil? They refer to oil viscosity, based on a scale established by the Society of Automotive Engineers (which is where the “SAE” comes from). The scale rates oil from a low of 5 to a high of 50. As you’ve probably noticed, most automobile motor oils have two numbers. These are multi-grade oils, which means they are non-Newtonian fluids.
The first number describes viscosity at low temperatures. The second number refers to viscosity at normal engine operating temperatures. Some examples: the “5” in a 5W-30 motor oil will protect an engine down to an air temperature of about -25 degrees Fahrenheit. The “10” in a 10W-30 is good if the lowest temperature where you live is likely to be in the neighborhood of -10 or so. As for the “30,” that is well-suited for the typical temperatures that most cars operate at these days. If you are driving a racing car, or pulling a heavy trailer on a hot summer day, you might want the higher-temperature protection afforded by a motor oil with a second number of, say, 50. (As for the “W,” it indicates that the oil is designed to work well in cold weather.)
In the old days, motor oils came in only the single grade variety. Back then, if you lived in a cold climate, you’d would have to use a different oil grades in different seasons, switching from an SAE 30 in the summer to an SAE 10W in the winter.
Which oil should you use? My suggestion: Refer to the owner’s manual that came with your car. It will tell which grade to select.
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