5w40 Vs 15w40 – What Are The Major Differences?

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A car is composed of hundreds of complex machines. When the engine starts, it’s these machines- as a combination- that keep the car moving. Keeping those parts and devices in working order is essential to keeping any vehicle healthy from day to day.

There are many tools to keep your car running smoothly. Lubricating oil is one of the materials used for auto maintenance. Transmissions, which require lubrication, use transmission fluid to complete that job. We’re going to compare two different motor oils and tell you which is best for you. 5w40 motor oil and 15w40 motor oil both possess similarities but they also have differences Some drivers choose to swap these out while others do not because they fear potential consequences like damage or increased wear on their vehicle’s engine over time; let us differentiate 5w40 from 15w40 so you can make an informed decision about what type of fuel will be right for your particular situation. Let’s see, 5w40 Vs 15w40 With Table.

DefinitionIt means that the name is sort of implanted along with a specification about its initiation to the provided process of oiling the engine.Synthetic 15w40 engine oil with better flow in low temperatures and shear stability.
ViscosityBrand Valvoline and viscosity 5w-40Brand shell and Viscosity 15w-40
Synthetic oil5w40 is full synthetic motor oil.15w40 is synthetic blend engine oil.
Used5w40 oil is suitable to use in winter.15w40 oil can be used in winter as well as summer.
Protection5w40 extra wear protection to keep engine parts like new.15w40 provides triple protection and technology that protects against wear.
ControlExtra detergents fight off sludge and deposits.Exceptional Deposit Control/Cleanliness.
ProvidesThe 5w40 Quickly starts and provides quick protection in cold weather.Synthetic 15w40 engine oil with better flow-in low temperatures and shear stability.
Thermal and oxidation5w40 motor oils have increased thermal and oxidative stability.The 15w40 engine oil has excellent high thermal and oxidation stability.
TemperatureThe design temperature of 5w40 engine oil does not exceed 5 degrees.The lowest temperature you can expect from 15w-40 engine oil is 15 degrees.
PriceThe 5w40 oil price is around $48-$52.The 15w40 oil price is around$37-$42. 

5w40 Vs 15w40: Major Differences

Built quality

The 5w40 engine oil is a multi-grade mineral-based oil. The name of the 15w40 engine oil is implanted along with its specification about initiating the process of lubricating an engine. This means that this type of 15w40 motor oil is formulated for use in engines where oil is multi-grade mineral-based oil.

Viscosity level

The two engine oils have different viscosities which happen to determine the reaction towards certain weather conditions. Viscosity implies how thick, sticky, or semi-fluid in terms of its flow it is. The 5w40 oil dictates that at max it should maintain a low temperature of 5 degrees Celsius under which the oil can flow well. It flows well below this temperature so as to function properly when winter arrives. Conversely, 15w40 oils, provide input for a minimum temp range of 15 degrees Celsius in order for them to be able to output lower and higher temperatures respectively within engines making these multi-grade products suitable for motor engines.


Detergents are present in the engine oil so that it can purify some of the oils. They are used to clean impurities from certain commodities, like mineral oils which have bits of metal within them. The 15W-40 engine oil contains detergent particles due to its nature as a mineral product and because they exist for use by humans. 5w-30 engines don’t contain any detergents and there’s no need for them: this is only relevant if you want your machine parts purified before using them.


Temperatures determine the condition or state of a substance, either in its solid or liquid form. There are ranges where temperatures are favorable and others aren’t. The 5w40 engine oil takes care of low temperatures (maximum 5 degrees) so it doesn’t turn into a liquid while maintaining its viscosity levels–in other words, avoiding getting spoiled by high temperatures at all costs! On the other hand, 15w40 engine oil is great for higher temperate environments (minimum 15 degrees), meaning you can use it during both winter and summer times without encountering any issues with your car.


5w40 oil is suitable to use in winter.  15w40 can be used in both summer and winter, but it’s more suited for the colder months of the year because it has a higher viscosity index than 5w30 or 10W-30 oils.


The 5w40 extra wear protection is a motor oil that has been formulated to provide maximum engine protection, which includes keeping it running like new. The 15w40 provides triple protection and technology that protects against wear by providing excellent lubrication for your vehicle’s engine system.

Thermal and oxidation

5w40 engine oils have increased thermal and oxidative stability. This type of oil is suitable for use in summer when the vehicle operates at high temperatures. The 15w40 engine oil has excellent high thermal and oxidation stability. It can be used all year round, withstanding higher operating temperature ranges than 5W30 or 10W-30 motor oils.

5w40 Vs 15w40: Similarities

Synthetic oil

5w40 and 15w40 both are full synthetic oil. Synthetic oils are made of molecules that do not occur naturally in crude oil, such as polyalphaolefin (PAO) or esters. These types of lubricants provide better protection against wear than conventional petroleum-based mineral oils because they have a higher viscosity index, meaning the fluid will be less likely to flow out from between two metal surfaces before there’s time for it to adhere and form a barrier.


The 5w40 and 15w40 both use Extra detergents to fight off sludge and Exceptional Deposit Control. This engine oil provides excellent protection for your vehicle’s internal components while keeping the exterior looking good with a glossy finish. It also features an advanced additive package that resists viscosity breakdown to keep engines running smoothly under all conditions.


5w40 and 15w40 both are grades of motor oil that provide quick starts, protection in cold weather, better flow in low temperatures, and shear stability. 5W-30 is also a grade of motor oil but provides less protection than the other two grades because it’s thinner to prevent engine wear during hot weather.

5w40 is Best for Viscosity

The 5w40 meaning of winter provides that the oil must have entailed a certain maximum viscosity or flow at low temperatures. The 5 stands for the oil viscosity at zero degrees, w stands for winter and 40 stands for oil viscosity at 100 degrees (Carcareninja). Under this mandate, it is necessary to apply an engine with a type of fluid capable enough in its application because it needs oils not too watery but also vicious enough in order to go through without causing any problems.


  • Due to good cleaning from impurities and almost no deposits occurring on the engine retains 
  • Its protective properties are longer than conventional oils which can lead to increased wear protection.
  • It also has better cold weather performance due to high viscosity at low temperatures.
  • It is more resistant to extreme conditions like those found in desert climates.


  • It can be used in engines that are not that worn out. 
  • Some manufacturers don’t agree with using 5w40 in their engines.

15w40 is Best for Protection

15W40 provides triple protection and technology that protects against wear. 15w40 is designed to provide three levels of protection: it prevents the engine from wearing out; reduces friction with metal parts such as pistons and bearings; and keeps the heat at an optimum level for fuel efficiency. This type of lubricant also has properties like detergents or dispersants which clean up deposits on surfaces inside the engine by removing them with a solvent-like action.


  • This type of oil suits cars that have worn-out engines, because it protects the engine better.
  • Prevents the formation of corrosive processes, promotes the removal of sludge; 
  • Provides more economical fuel consumption in the internal combustion engine, with a high degree of wear.
  • The oil is cheaper to make and good for engines in warmer environments too.


  • Not the best option to choose when operating at low temperatures.
  • Not able to maintain its viscosity if you have a more aggressive driving style.


Is 15w40 better than 5w40?

The 5w-40 has a broader operating range than the 15w-40. Unless you’re trying to save money or are misinformed about synthetic oils, it’s an unwise decision to pick the 15w-40 option. There is only one benefit of using 15w-40 oil though: they will maintain their 40-weight viscosity for longer periods of time than oil that starts at 5W.

Is 5w40 thinner than 15w40?

In general, 5W-40 and 15W-40 have the same viscosity at operating temperature. One will not be thinner or have a lower viscosity than the other. Both will have a 40 grade of viscosity.

Can you mix 5W-40 with 15W-40?

Let’s say you’re mixing a syn with a dino. Or, let’s just do it the other way around and say you’re blending an x brand of oil with 15W-40. The two different base stocks will not spontaneously combust into one another and cause your engine to throw out its rod.

Final Words

When choosing an engine oil, first of all, one needs to rely on its viscosity. Check with your car manufacturer or read the manual for recommendations. Secondly, it is necessary to take into account the condition of the car and what conditions you will be operating under in order to make a choice as to which oil is best suited for your vehicle.

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