The Different Weights in Motor Oil

February 15th, 2009 by Justin

If you are looking at motor oils for your truck, SUV or Jeep, you probably have seen a lot of numbers and letters. Unfortunately, motor oil can be confusing for consumers to buy. And finding the right motor oil for your vehicle’s engine is very important. Here are some tips on choosing the right motor oil.

Check Your Owner’s Manual First
Your vehicle manufacturer has spent billions of dollars creating your vehicle, so they know exactly what should be going into it. Your manual will tell you exactly what to use. However, here is a guide so that you can read the labels once at your auto parts store.

Motor Oil

What are All Those Numbers For
When you shop for motor oil, you will see plenty of numbers and letters. For instance, you will usually see a motor oil with SAE, W and S or C.

SAE
SAE stands for the Society of Automotive Engineers and this organization has come up with a scale of how to categorize the different motor oils around.

W and the Following Numbers
You might see the letter “W” next to a number such as 10W, 5W, 40W, etc. W stands for winter temperature. This is usually the coldest temperature that your oil should operate in. For instance, if you live in a cold environment, you want motor oil with a low temperature viscosity. Viscosity is defined as how thin and easy to flow something is. For instance, water flows pretty easily, jelly does not. So for instance oil with 5W means that the viscosity is made for engines operating in 5 degree Celsius winter weather. On the other hand if it is the middle of the summer and you live in Texas, you want an oil that is more durable to the heat. You may want to purchase 40W for your car.

Multi-grade Motor Oil
Besides single grade motor oil, some motor oil can be multi grade made for a variety of temperatures such as 10W-30W. This is done with special chemical additives.

S or C
When you see the letter S, this means for spark ignition vehicles- generally for passenger vehicles. The C stands for commercial vehicles.

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