The Difference Between 10w30 & 10w40

Last Updated on January 30, 2023 by Leepu Da Maxim

10w30 is a lighter-weight, more viscous oil that has been engineered for use in hot climates where it needs to flow better under high heat. 10w40 is a heavier, less viscous oil designed for cold temperatures where it doesn’t matter how well the engine flows.

Key Takeaways

  • The main difference between 10w30 & 10w40 is the thickness or viscosity of the oil at the operating temperature
  • If you are driving in the low temperature then 10W30 will be the best option for you
  • If you are driving in the high temperature then 10w40 will be the best option for you
  • You can use 10w30 in both gasoline and diesel engines which is very convenient

What Is 10w30 Oil?

What Is 10w30 Oil

10w30 is a type of 10-weight oil that has been designed for use in hot climates. It’s not good to use 10w40 in the winter because it doesn’t offer as much protection from cold temperatures, but 10w30 can be used even when there are freezing conditions; 10w-30 has an API rating and high heat resistance to withstand colder weather without compromising its effectiveness.

Features Of 10w30

1. 10w30 is a type of oil that can be used in vehicles

2. It’s best for cold climates and provides the appropriate amount of lubrication

3. The viscosity, or thickness, helps to reduce wear on parts like the engine 

4. This type of oil also has good resistance against heat and increases gas mileage 

5. 10w30 may not be suitable for use in some newer cars because it doesn’t meet emissions standards

6. It’s important to always consult your owner’s manual before using this type of oil so you know if it will work with your car!


1. 10w30 is a heavier oil that provides better engine protection against cold starts

2. 10w30 has a higher viscosity, which means it’s able to withstand high temperatures without thinning out

3. 10w30 is less likely to break down and lose its lubricating properties over time than lighter oils so it will last longer in your car 

4. The thicker consistency of the oil makes it easier for seals and gaskets to seal properly because there’s more pressure on them when the engine is running

5. It can be used in both summer and winter climates with no changes or adjustments needed 

6. some vehicles require this type of oil specifically, such as older models of Mercedes-Benz cars made before 1995 or BMWs from 1987 onwards


1. 10w30 is a light-grade oil that will not protect your engine needs

2. 10w30 will burn at lower temperatures, which can lead to increased wear and tear on your engine

3. 10w30 does not have the same performance capabilities as other grades of motor oils; it may also cause fuel economy problems

4. If you are using an older vehicle or one with high mileage, this type of oil may be too thin for optimal lubrication 

5. The cold-weather properties of 10w30 are minimal – in colder climates where winter driving conditions exist, this type of oil would likely need to be changed more often than a heavier grade

6. In hotter climates where summer driving conditions exist, an oil such as 5W20 would work better because it offers better heat resistance.

What Is 10w40 Oil?

10w40 is a type of motor oil that has been designed for use in cold climates. It’s still recommended for drivers who don’t change their car’s engine oils often, but 10w-40 was created to withstand the demands placed on it by colder temperatures and make up for high-demand times when thinner oils may need to be used more often (such as during periods of intense driving).

10w40 contains both thin and thick types of oil. Delicate oils have less viscosity than thicker ones; they are lighter and flow more easily into tight spaces or underseals where heavier grades might not reach. Thicker oils stay longer because they have higher viscosities, which protects metal surfaces from corrosion better than other types of fat. 10w40 is a lighter-weight type of motor oil with a higher viscosity index than different grades. It provides better protection in cold temperatures than 10w30 or 10w50 (some drivers use it for high-demand periods).

Features Of 10w40

1. 10w40 is a type of oil used in engines

2. It’s made up of two different types of oil, one thicker than the other

3. The thinner oils are designed to flow more easily and lubricate parts quickly 

4. The thicker oils are designed to stay put on metal surfaces and prevent corrosion from forming as quickly

5. 10w40 was created for use in cold climates where there would be less demand for thin oil because it wouldn’t need to flow as much or get into tight spaces as often 

6. This type of oil is also good for people who drive their cars regularly but don’t always change the engine oil right away; it can withstand heat better than thinner oils without breaking down over time


1. 10w40 is a lighter-weight oil

2. 10w40 has a higher viscosity index than other oils

3. 10w-40 provides better protection in cold temperatures than other oils

4. 10w-40 has better fuel economy than other oils

5. The price of the product is usually lower for this type of oil 

6. It takes less time to change your car’s engine oil with this type of product because it drains faster and doesn’t need to be replaced as often, which saves you money on labor costs


1. 10w40 is not a good oil to use in the winter

2. 10w40 does not have as high of an API rating as other oils, which means it’s less resistant to heat and cold

3. 10w40 is more expensive than other engine oils because it has a higher viscosity index

4. You can’t mix different weights of oil, so if you’re using 20w50, for example, your engine will be getting too much lube

5. The thicker the weight of oil used in your car’s engine, the greater potential there is for leaks and dirty exhaust pipes

6. If you don’t use synthetic oil (which isn’t always recommended), then your car may need its fluids changed every three months instead of every six months due to increased wear on engines without synthetic lubricants.

What’s The Difference Between 10wt VS. 20wt Oils?

It comes down to viscosity index: 10 wt oils are thinner than 20 wt oils like 10w50. A car will need its fluids changed every three months with light oils because they don’t protect metal surfaces. 10w-40 is a lighter-weight type of engine oil with higher viscosity index than other grades that provide better protection in colder temperatures.

What Does 10wt Mean?

Ten wt (or 10 CST) means it’s thin at 100 degrees Fahrenheit and only comes out as ten on the dipstick, which means it doesn’t flow well or protect metal surfaces very much because motor oils thicken over time; 20wt (or 20 CST) can be thinner or thicker depending on where you are and what your climate demands. Heavyweight oils like 20w50 will last longer but may cause leaks if they’re not mixed properly. If you use synthetic oil, then your car won’t need its fluids changed every three months, and some 10wt oils may be more appropriate in cold weather, but 10w-40 is the engine oil for drivers who want to ensure their engines will last as long as possible.

Does 10W40 Hurt The 10W30 Engine?

No ten-wt oils are designed for engines that don’t require a lot of oil flow like 10w30; 10w-40 is a type of engine oil with higher viscosity index than other grades. 10wt oils can hurt an older car because the thicker they get, the more difficult it becomes to protect metal surfaces from corrosion, and leaks may develop if not mixed properly.

How Many Quarts In 10W40?

It could be anywhere between seven or eight quarts, but it’s typically around six, depending on your make/model car. It might take longer to change your vehicle’s fluids with this type of product due to its weight and thickness–although some people will argue that 10wt products offer better protection over time, so 10w-40 is worth the investment.

How Often Do 10wt Engine Oils Need To Be Changed?

It can depend on how much you drive and what type of 10-wt product you have, but 10w30 will last longer than 10w40 because thinner oils are better for engines that don’t require much oil flow like older cars’ small motors with low volumes. If your vehicle requires thicker 10wt products, then more frequent changes may be necessary based on age and miles driven. Some people argue that synthetic products reduce this frequency requirement from six months to four months depending on the make/model vehicle, year manufactured, etc. Generally speaking, it’s best to change every three months if possible unless otherwise specified by manufacturer recommendations in your owner’s manual.