What Do Different Motor Oil Weights Mean?
Car owner sometimes have a moment of complete bewilderment when it is time to have an oil change. The service people at the automotive care center talk about 5w-30 or 10w-30 oil and ask the person to make a decision which one to use. This is a moment when the owner just throws up his or her hands and says “whatever!”. This happens because that individual honestly does not know what the service person is talking about. Information helps a person make better choices on what to do, and having an idea of motor oil weights allows for better decisions.
The terms 5W – 30 or 10 W – 30 speak to the viscosity of the oil. It is referring to the speed of the oil flow that has been measured through a viscometer. The thicker, higher, the viscosity registers means that the oil is flowing slower. If the viscosity has a W, this means that the viscosity of the oil has been tested at colder temperatures. That designates the oil as a winter grade. Those numbers that don’t have the W were tested at 210°F, the approximate temperature of an engine while in operation. To interpret the viscosity 5W-30, it means that an SAE 5 motor oil can perform at a colder temperature (-25°F) but has the viscosity that would be found in an SAE 30 at 210°F. In other words, there will be a quick flow of oil when it is started cold. That results in less dry running and that in turn means lower engine wear. The 5W-30 oil is thin enough for cold starts and at the same time the oil is thick enough to be allow for starts when the engine is much hotter. Additives in the oil will allow the viscosity to get thicker as the temperature rises. It is an almost perfect situation for someone who lives in a colder climate.
Knowing this helps the car owner better understand what is being put into his or her vehicle at the oil change. The owner’s manual will give information as to the right viscosity. It helps the consumer to know about the American Petroleum Institute (API) Certification. The API – certified oil has the starburst logo of the API stamp on the oil container. A person who is doing the oil change as a do-it-yourself project will know immediately that the oil product meets all performance standards of the API. Something to remember is that a higher viscosity oil will provide no benefit in a car that the owner’s manual says should have a lower weight. Although a higher weight could be used, there is nothing gained. This means that if the owner’s manual calls for a 30 weight, using a 40 weight is not going to create an advantage.
What is interesting is that there is a move towards thinner oil being used in the engines that manufacturers are recommending an SAE 5W-20 be used, when in the past the type of oil recommended was SAE 5W-30. The reason for this is that the thinner oil is going to have greater fuel efficiency. The thinner oil is also better for the engine. There is less friction and wear on the engine because the oil is moving faster.
The question of the use of synthetic oil comes up and a consumer can wonder about whether or not the synthetic variety should be used. It is more expensive than the oil more conventionally used. The advantage is that synthetic oil, because it is man-made, is able to handle both extreme hot and cold temperatures.
If a consumer is still a little bit confused, the best oil to be used can depend on driving conditions. A thicker oil may be best if there is a lot of high elevation driving or pulling heavy wagons. This is because the thicker oil can handle contaminants. The engine will wear faster if the contaminants that enter the oil are more than the oil thickness. Thicker oil can handle bigger contaminant pieces. Climate is definitely going to make a difference and people living in colder climates will want to see the W. The age of the engine may also be part of the equation. But knowing what the oil weights stands for is going to help whenever an oil changes made an automotive care center. When a mechanic recommends a certain type of oil, the owner will know immediately what the mechanic is talking about.