Using the right motor oil for your particular engine is very important. When choosing the oil that you want to use, you must always take into account the viscosity of the oil that you are buying. Viscosity refers to an oil’s thickness and this must be appropriate for your engine. You can find the proper viscosity needed for your vehicle in the owner’s manual.
To keep your engine running properly for as long as possible, use the best oil that you can afford. This is a key to getting the best performance out of your engine, year in and year out. It is also important to change your oil at the appropriate times.
Many people are familiar with the designations such as 10W-30 or 20W50, but are not sure what these numbers mean. Here is a brief explanation that may help you better understand why you need to use the right viscosity of oil.
When oil is rated for its resistance to floe (viscosity), it is rated at 0 degrees F. This is shown by the number that comes before the “W”, which stands for “Winter”, and then rated again at 212 degrees F which is shown by the second number. In other words, 10W30 oil will have less viscosity when it is cold or hot than an oil that is rated at 20W50.
Keep in mind that oil will become thinner as it is heated. It will become thicker as it begins to cool. The second number will be higher for oils that are more resistance to thinning out. For instance 10W40 compared to 10W30. This is a good thing and should be kept in mind when choosing oil. However, one should remember that oil that is somewhat thicker will often do a better job of sealing. Thicker oil will also provide a better lubrication film over the parts.
While all of that is good, the oil cannot be too thick or it will not flow as well as it should. Also, thick oil can cause the engine to work harder when during starting. For many vehicles, an oil that is rated 5W is suggested for use during the winter months. Some synthetic oils have been created that will flow easily even during cold spells. These are often designated with a 0W rating.
After the engine has been on and the oil has heated, the second number tells us the oil is able to stay thicker at these higher temperatures and the higher this number the longer the oil will remain thicker.