Back to all

Oil's Well That Ends Well (Oil Change Grades and Weight)

March 30, 2025

Changing your oil regularly is one of the most important things you can do to keep your vehicle running well.  And knowing the right type of oil to use is also very important. 

Engine oil is classified by weight, but it doesn't refer to how much the oil would weigh if you put it on a scale.  It refers to viscosity, or how easily the oil flows through the engine.  Most engines operate normally at around 210°F/99°C.  The viscosity, or weight, is assigned a number by how well it flows at that temperature.  The lower the number, the more freely it flows. 

Most vehicle engines use what's called a multigrade oil which behaves differently in different temperatures. Multigrade oils have a "W" in their viscosity number that you may have seen on a bottle of oil, something like 5W30.  The W stands for winter and shows how freely it flows in colder temperatures.

That means a 5W30 oil will behave like a 5 weight oil in lower temperatures (less viscous or thinner) and a 30 weight oil in warmer temperatures (more viscous or thicker).  That's important on a cold day because the oil needs to behave like a thinner oil when you start your engine since it need to lubricate engine components immediately to protect the metal components. Then as the engine warms up, it behaves like a thicker oil to prevent friction among those parts.  Pretty neat trick, right?

The type of oil you use can differ depending on what type of climate you operate your vehicle in and how your vehicle is used (carrying big loads, towing, etc.). Your owner's manual contains several different recommendations based on these factors.  Your service advisor can recommend the right oil for your needs.  Like Shakespeare said, "Oil's well that ends well."

Tuffy Joliet (South Plainfield)
2031 SR 59
Joliet, Illinois 60586
815-436-1829

More articles from Tuffy Joliet

U and your U-Joints (Lubricate U-Joints)

July 27, 2025

If your vehicles power goes to the rear wheels, then you have something called U-joints in the drivetrain. U-joints are connectors that allow the rotating power from your vehicles engine to deliver its power through a driveshaft to make the rear wheels rotate. You need U-joints because the surfa... More

Strutting Your Stuff (Shocks and Struts)

July 20, 2025

Ever wonder how your vehicle is able to move over bumps, potholes and other irregularities in the road and you hardly feel a vibration in the cabin? Its your shocks and struts doing the hard work along with the rest of your suspension and tires. They keep the ride smooth and are important for yo... More

A Hot Mess (AC System-Compresser)

July 13, 2025

Air conditioning used to be a real luxury in a vehicle, but now it's standard in most. Your vehicle's air conditioning system is built to last a pretty long time, but like anything mechanical, sometimes it fails. It helps to know a little about how the A/C works. There's a compressor that press... More