What’s the Difference Between 5W40 and 5W30?

3 min read
What’s the Difference Between 5W40 and 5W30?

It can be intimidating to be faced with so many options for engine oil when you're at an auto shop or garage. Here are two options that frequently confound drivers: 5W30 and 5W40 These might appear to be mysterious codes, but they are crucial markers of the oil's behavior in various scenarios. Together, we will decipher these numbers and letters so you can make an informed decision.

Describe 5W30

One kind of multigrade oil is 5W30. The '5W' denotes the oil's flow characteristics in the winter ('W' stands for winter). Here, a lower number indicates that the oil is less viscous and will flow more easily in colder weather. The viscosity of the oil at 100°C is represented by the '30'. This means that it functions as a 30-weight oil at standard engine operating temperatures.

Describe 5W40

Like 5W30, 5W40 is an oil with multiple grades. Because of the '5W', it has the same 'winter' viscosity. The '40', however, suggests that this oil is marginally more viscous than the 5W30 at 100°C. This results in a thicker oil film at operating temperatures, which in some circumstances may be beneficial.

What Separates 5W30 from 5W40?

At a glance, the primary distinction is their respective viscosities at operating temperatures:

  • 5W30 is less viscous at 100°C, meaning it's a bit thinner.

  • 5W40, being more viscous at 100°C, offers a thicker protective layer for engine parts.

Knowing the Features of Oil

Multigrade oils, like 5W30 and 5W40, adjust their viscosity depending on the temperature. When cold, they're designed to remain fluid (like a low-viscosity oil) to ensure smooth startup. As the engine warms up, it behaves like higher-viscosity oils to provide adequate protection.

The decision between these two usually boils down to:

  • Engine Manufacturer Recommendations: Always consult your vehicle's manual. Manufacturers often specify oil types based on extensive testing.

  • Driving Conditions: If you frequently drive in demanding conditions (e.g., towing heavy loads, high-speed driving), a thicker oil like 5W40 might offer better protection.

  • Engine Wear and Age: Older engines or those with high mileage might benefit from the enhanced protection of a more viscous oil.

The Impact of Weather on the Type of Oil

The selection of oil is significantly influenced by the ambient temperature. Although 5W30 and 5W40 are both made to perform well in cold starts,

A 5W40 oil may be preferred in warmer climates or during the sweltering summer months because of its thicker consistency at higher temperatures, which offers better wear protection.

On the other hand, 5W30 can provide a good mix between protection and efficiency in moderate climates.

Summary of 5W30 vs. 5W40

  • 5W30 offers better fuel efficiency, is suitable for regular driving conditions, and is often recommended for a broad range of vehicles.

  • 5W40: Delivers enhanced protection in demanding conditions and might be preferred in hotter climates or for vehicles undergoing heavy-duty operations.