Updated at: 04-03-2022 - By: micdot

There are many different types of motor oils, and the thickness is what distinguishes them. Let us know which oil is the heaviest by filling out this form. Let’s get started. In other words, what’s the heaviest motor oil there is? A 40w-70 is what you need. There’s no thinner for this stuff. Using a rating system, motor oils can tell you more about the thickness of the oil they use. This rating system was devised by the Society of Automotive Engineers (SAE). The viscosity of the oils will be used to classify and differentiate them in this grading.

When we talk about viscosity, we’re referring to the fluid’s resistance to flow. Water is an example of a low-viscosity liquid. The viscosity of water is quite low, making it a thin liquid. Since other liquids are thicker than water, they are known to have a higher viscosity. Motor oil viscosity might also alter. A change in viscosity measurement will occur if the temperature of the motor oil is increased or decreased. The term “viscosity,” which is still misunderstood by some, simply refers to “thickness.” Viscosity refers to how thick or thin an oil is. Having a high viscosity indicates that the oil is thick. Let’s get into the nitty gritty of the thickest engine oil now.

What Is The Thickest Engine Oil?

The 40w-70 motor oil is the heaviest on the market. The viscosity grade of the motor oil has an impact on the oil’s thickness. The oil will demonstrate more resistance if its level of tensile strength is higher. This is because new polymers have been added to the multi-weight oils, making them more familiar.

When using 40w-70 oil, keep in mind that the viscosity of the oil is determined by the number forty, which is present in the formula. On the other hand, the viscosity during the procedure is defined by the number seventy.Helps keep oil from seeping into the valve guides if it has a high operational  viscosity. It will also keep it out of the chamber where it will be burned.

Where Do You Use 40w70?

In racing circumstances, you can utilize 40w-70. Additionally, because diesel engines tend to burn oil at a high rate, this particular motor oil is designed for older cars with diesel engines. In a wide variety of temperatures, multigrade viscosity motor oils can perform.

So you need to know how and where to apply 40w-70. So, familiarize yourself with the multi-grade viscosity motor oils before you do anything else.

What are the pros and cons of 40w70?

As a 40w-70, there are both pros and drawbacks to consider. The pros and drawbacks of 40w-70 are important to know so that you can decide whether or not to use it and whether or not this engine oil is compatible and suited for the engine you intend to use it in.


40w-70 has a few advantages over other types of light bulbs. For the most extreme protection and performance, some items are available. In addition to being thick, we all know that a higher viscosity in motor oil means better performance for your car.

In addition, 40w-70 can assist avoid engine wear and oil loss. Heavy loads are also better guarded against by a viscosity that is thicker. This engine oil is also able to retain its oil pressure and viscosity even in the most extreme conditions. Using a 40w-70 can also help cut and minimize oil consumption and limit the need for refueling. In addition to reducing emissions, it also helps to keep the oil pressure in the engine constant. As a result, there are many advantages to employing a 40w-70.

There are, however, a few points to keep in mind. First of all, 40w-70 is not advised for every vehicle. The first thing you should do is consult a professional or your owner’s manual. The recommended oil grade for your vehicle can be found on this page. The owner’s handbook should always be followed, and only the recommended grade of oil should be used. Your car could be damaged as a result.


The 40w-70 has numerous advantages, but it also has several drawbacks. Many drivers make the mistake of constantly selecting motor oil with a viscosity that is higher than the required amount. A motor with a high viscosity level would be ideal for their vehicle, since they believe this to be a must.

You must keep in mind that this isn’t always the situation. Motor oils with high viscosity levels aren’t always the best choice. It would be beneficial if you followed the manufacturer’s recommendation for your vehicle and yourself. First of all, heavier motor oil means that your engine will have a more difficult time circulating the oil. When the oil in your engine isn’t being circulated properly, you’ll notice a decrease in fuel economy. This will also make it more difficult to start your vehicle. When your car is difficult to start, your engine will suffer more wear and tear as a result. The disadvantage is already worse in warm weather circumstances; it will get even worse in cold weather.

If a motor oil is too thick, it will not be able to transport heat between the various parts of the vehicle’s engine. This is a negative.

Should I Use Thicker Oil In A High Mileage Engine?

The answer is no. High-mileage cars don’t always necessitate heavier oil. Always consult your owner’s handbook and seek advice from specialists in the field.

It’s not a good idea to use a motor oil based on personal preference. Please seek the advice of an expert.


According to the thickness of the motor oil, there is a difference. 40w-70 is the thickest motor oil.

When to utilize 40w-70 must be a skill you have mastered. The thicker the viscosity of the oil, the more complicated the movement of the oil in the engine is.