Facts about Motor Oil

Whether you have a car or a motorcycle, how to find the best motor oil is one of the most important things you want to learn. This article provides all the fact you need to know about choosing motor oil.
Typical inspection data is data provided by oil companies. This data is calculated by averaging common chemical properties data and actual physical properties data. The way to get the typical inspection data is to contact the oil companies directly or ask the distributor of the oil. This data is easy to get and can be very useful if you are willing to look into it. In this article, six oil properties from typical inspection data are introduced and analyzed for your convenience.

Viscosity

The viscosity of oil measures how flowable the oil is. As it is known, flowability is the most important factor for motor oil, thus viscosity is the most important property for engine. Viscosity, by definition, is a property of oil that can create sheering flow stress and continuing flow resistance. The thicker the oil is, the higher its viscosity is. In fact, viscosity cannot be too high or too low because oil will either loose film strength in high temperature or can’t be pumped to certain parts in low temperature. Multi-viscosity oil is the result of the greatest improvement in oil. The way to choose multi-viscosity oil is to use a multi grade with the narrowest possible span of viscosity.

Pour Point

Pour point is defined as the lowest temperature at which oil will pour or flow under prescribed conditions, also known as the temperature that is 5 degrees above the point at which no movement on surface shown by chilled oil for 5 seconds when oil is inclined. The pour point is extremely important if your vehicle is to be used in winter. The way to judge oil by pour point is easy: the lower, the better. As some manufacturers provide borderline pumping temperature, the easiest way to find the pour point is by taking 20 degrees F out of the borderline pumping temperature.

Viscosity Index (VI)

Viscosity index is an arbitrary measure, a number that indicates change of viscosity with different temperature. The higher the viscosity index number is, the lower the change is. Thus oil with higher number of viscosity index is better. But viscosity index does not indicate the oil ability to resist thermal breakdown. This property is essential for keeping bearings well. When you are comparing viscosity index numbers, make sure to do it within a viscosity range.

Flash Point

Flash point of oil is the lowest temperature that can make oil vaporize to form an ignitable mixture. So with a flame held over the mixture, it can be ignited. Oil tends to suffer vaporization loss or burn off on hot walls in high temperature when the flash point is too low. So you have to be careful when choosing oil. In fact, the higher flash point, the better the oil is. If you have to choose oil that has a low flash point, 400 F is the lowest flash point acceptable. Be careful with this flash point, because oil with a flash point lower than 400 F means high consumption and thus a waste of money.

Percentage of Sulfated Ash

Percentage of sulfated ash tells you when oil reacts with sulfuric acid and burns, how much solid material can be left. This percentage of sulfated ash is a measure of the detergent additives and metallic anti-wear in oil. For example, zinc dithiophosphate as mentioned below is reflected in this percentage of sulfated ash test because it is used as a common detergent and anti-wear additive.

Percentage of Zinc

Percentage of zinc is a measure of the amount of zinc dithiophosphate used in oil. Zinc is always used as an extreme pressure and anti-wear additive and is only used when actual metal-to-metal contact exists in engine. In case this rare metal-to-metal contact happens, zinc can prevent wearing of the engine. The percentage of zinc should at least be above 0.11% under normal circumstances. But if you have turbo-charged vehicles or air-cooled motorcycles, higher zinc percentage might be more desirable.

When selecting motor oil, keep these six properties in your mind and compare them as mentioned above. Get ready for a cheap and safe ride with your No. 1 choice of motor oil!