What Is Engine Oil?

Engine oil is the lifeblood of any vehicle. Without it, an engine wouldn’t last five minutes before locking up. That’s why sticking to the oil specs in the vehicle handbook is crucial.

Motor oil is all about viscosity, which is just a fancy way of saying how thick or thin a liquid is. Multi-grade oils like 0W-20 and 5W-20 have different thicknesses at various temperatures.

So, is 5W-20 better than 0W-20? Are either of them good for a ride? And which one should be used when topping up? Let’s dive in.

A Quick Note on Viscosity

Viscosity is key to understanding multi-grade oils. Simply put, it’s how dense a liquid is. A thicker liquid flows slower, while a thinner one zips right out. Think of custard versus water—water flows easily, while custard takes its sweet time.

The same goes for engine oils. For instance, SAE 10 is less viscous than SAE 20, meaning it flows better.

What Is Multi-Grade Engine Oil?

0W-20 and 5W-20 are prime examples of multi-grade oils. These are the go-to choices for most modern vehicles, especially in climates where extreme cold isn’t an issue. Multi-grade oils come packed with additives that help them behave differently at various temperatures, making them versatile for year-round use.

Back in the day, drivers had to switch oils with the seasons—thinner oil for winter and thicker for summer. Multi-grade oils have changed the game, letting one oil do the job all year round.

Some perks of multi-grade oils include:

• Less strain on the battery during cold starts.
• A healthier engine overall.
• Better fuel economy throughout the year.
• Improved performance in hot conditions.

Sure, they’re a bit pricier, but they’re worth it for the long haul.

What Are Viscosity Modifiers?

Viscosity modifiers, or VI enhancers, are the secret sauce in multi-grade oils. These polymer molecules change with temperature—expanding when it’s hot and contracting when it’s cold. Picture a slinky: when it’s cold, it’s all coiled up, but as it warms, it stretches out.

These modifiers help keep oil thicker at high temperatures, giving winter oils the ability to perform in summer heat.

Understanding SAE Engine Oil Grades

SAE grades, like SAE 20, come from rigorous testing by the Society of Automotive Engineers. They measure how oils behave at freezing and boiling temperatures, giving each oil its “W” (for winter) rating and its operating temperature grade.

In simpler terms, the lower the number, the thinner the oil. So, 0W-20 is pretty thin compared to others.

0W-20 vs. 5W-20 – What’s the Difference?

Now that the basics are covered, let’s get to the nitty-gritty. 0W-20 has a viscosity of SAE 0 when cold, while 5W-20 is SAE 5 in the same conditions. At normal operating temperatures, both oils perform similarly, equivalent to SAE 20.

So, what’s the takeaway? 0W-20 flows better in the cold, making it easier for engines to start on chilly mornings. But it might not coat the engine as well before it warms up. Both oils are designed for smaller, efficient engines, so they’re not ideal for heavy-duty vehicles.

Can 0W-20 Replace 5W-20?

Got some 0W-20 lying around? It might be tempting to swap it for 5W-20. But should it be done? The answer lies in the owner’s manual. If it says 0W-20 is okay, then go for it. If not, stick with what’s recommended.

While the differences between the two oils are minor, using the wrong one could lead to issues, especially in extreme weather. If problems arise, it’s best to switch back to the recommended oil ASAP.