Motor Oil- Let's Talk Types and Intervals

Change your engine’s oil every 3 months or 3,000 miles. This wisdom has carried down through the ages (okay, the last hundred years). But the wisdom, she is a-changin’. 

News flash: Current vehicles don’t require such frequent oil changes. Oh, you knew that one? Fine. Did you know that most manufacturers use the terms “motor oil” and “engine oil” interchangeably? Man, you’re good. Okay then, how many types of oil are there? What about grades? Yeah, it gets a bit hazy there for most of us.

Oil label.

Types of Motor Oil

• Conventional: The original motor oil. Refined crude oil that provides some lubrication but needs to be changed more often. Good thing it’s cheap.

• Synthetic: Created in a lab with additives for better viscosity and lubrication. This oil can last much longer (up to 20,000 miles) but is more expensive.

• Synthetic Blend: A combo of conventional and synthetic, this oil has some components of both. It lasts longer than regular conventional oil, but not as long as synthetic. It is a middle grade option.

• High Mileage: Specially formulated for vehicles with high mileage, usually over 75,000. It can also help reduce fuel consumption by keeping the engine lubricated well enough that it uses less energy to operate. But all this comes with a hefty price tag. Definitely worth it for people who put a lot of miles on their vehicles.

Grades of Motor Oil

Today there are a numbers of motor oil grades available. Each grade has been specifically designed for certain conditions. If you take a look at the label, you’ll see a combination of letters and numbers. This feels a lot like a secret language, but if you know the code it’s easy to figure out.

For example, let’s look at grade 5W-40. The W stands for winter. It indicates how viscous the oil is before the vehicle’s engine gets up to the normal operating temperature, otherwise known as winter grade.

*Quick Physics Lesson: Viscosity represents the amount of internal friction in a fluid.*

The number before the W shows how effective the oil is in winter conditions. A lower friction rate allows for better flow, so 5W will flow easier in cold temperatures than 10W.

The second number indicates how thick the oil is under ordinary operating temperatures, or summer grade. A higher number here, like 40 in our example, shows that the oil is thicker and less likely to thin out at higher temperatures. A vehicle in warm climates might benefit from grades 15W-40 or 20W-50. But colder climates reach for the 5W-30 or even 0W-20.

There are 14 main grades of motor oil identified by the SAE (Society of Automotive Engineers). These include 6 winter grades (0W, 5W, 10W, 15W, 20W, and 25W) and 8 summer grades (8, 12, 16, 20, 30, 40, 50, and 60). Manufacturers combine these to cover the different temperature ranges. The most common grades are 0W-20, 5W-30, and 10W-40.

Also, be aware that some manufacturers use licensed specifications which can have more additives for certain reasons.  Examples include BMW LL-17 FE+ or Volkswagen/Audi 504 00, 507 00.

Gloved hand holding an oil dipstick.

Oil Change Intervals

Now here is where things get interesting. The very best advice is to dig your owner’s manual out from under your Dunkin’ napkins and emergency granola bar in your glovebox and see what the manufacturer says. Some cars can go 7,500-10,000 miles (6-12 months) in between oil changes.

But you sure don’t want to risk going too long. Believe me. I had a cracked engine block at age 17 to educate me early. Don’t be 17-year-old me.

The way you drive can also affect oil change intervals. Manufacturers call theses “severe use”.

• Frequent, short trips

• Heavy towing

• Driving in extreme hot or cold temps

• Regular commutes in stop-and-go traffic

Another thing to consider is those very short trips. Take a look at your elderly neighbors. They only drive to church three blocks away and the grocery store six blocks away. That engine never gets up to the temperature it needs to evaporate the condensation. It generally takes driving about ten miles to do that.  This is also considered severe use.

Red oil pressure dashboard light.

Signs You Should Get an Oil Change

• The oil change light comes on.

• The oil is dirty and gritty instead of a clear, amber color.

• You are hearing any strange engine noises, like a knocking.

Best practice even in high mileage oil use and conservative driving patterns is to get your oil changed twice a year. Your friendly mechanic can answer any questions you have about your specific car and keep your engine running smoothly.