Three Things Your Auto Engine Oil's Number Is Trying To Tell You

The string of numbers and letters used to describe each type of engine oil isn't too long, but is nonetheless confusing if you don't know exactly what each number and letter stands for. Here are three things the number tells you about the oil you're putting in your vehicle.

1. Whether it's designed to function in various temperatures.

If your oil number has two parts separated by a hyphen, one of which has a W in it, that means your oil has different thicknesses at different operating temperatures. The thickness, called "viscosity," is crucial to engine function because thinner oil flows better and can access tighter areas of the engine, but also provides less sturdy lubrication when it gets there.

The reason good engine oil has two viscosities listed is because oil is thicker when cold and thinner when hot, which means that in its natural state it may end up being too thick to flow in a cold engine or too thin to lubricate a hot engine. Additives help keep the oil thinner when cold to provide better flow and thicker when hot to provide better lubrication.

2. "Winter" viscosity.

The W mentioned above stands for "Winter," which basically just means that the number it follows refers to the thickness of the oil when cold. The reference to winter doesn't necessarily mean the oil is customized for cold climates or the winter season, it just refers to the oil's thickness when you start running the engine but it isn't up to operating temperature yet. A lower (that is, thinner) winter viscosity is better for your engine because if the oil is too thick to coat the engine well when cold, your engine basically has to run without lubrication until it reaches operating temperature. This is especially bad if you have a short commute, because your engine won't have time to get to operating temperature before you turn it off again.

3. Operating temperature viscosity.

The operating temperature viscosity is described by the number that comes after the hyphen. It's also crucial because it describes how thick the oil will be after the engine has been running for a few minutes. This means that any time you take a trip of any length, this number will apply for most of the trip. Additives are used to make the oil thicker at operating temperature so that it will lubricate the engine better; however, additives degrade over time, leaving the oil thinner and less effective at operating temperature. This is one of the reasons it's crucial to get regular oil changes.

These three specifications can all be derived from the number used to describe your engine oil. To ensure you have the correct grade of oil for your engine, follow manufacturer recommendations for the vehicle. Contact a service like auto repair by Accurate Transmission & Auto Centre Ltd for more information or assistance.