Transmission Fluid Vs Engine Oil – Everything You Need to Know!

Transmission fluid and engine oil are two distinct liquids designed for different purposes, yet many people confuse them and end up ruining their cars by using the wrong one.

In this post, we are going to explain everything you need to know about transmission fluid and engine oil so that you can have a better understanding.

About Transmission Fluid

Many people understand the significance of changing engine oil regularly, but few realize how equally essential it is to change transmission fluid too. That is because transmission fluid acts as a lubricant, keeping all your vehicle’s gears and clutch pack lubricated.

A properly lubricated gear system ensures your car shifts smoothly, without any damage – particularly when driving a manual-based vehicle.

Unfortunately, over time your transmission’s fluid will begin to deteriorate due to a buildup of metal debris and heat from driving.

In some instances, you may even observe your transmission fluid changing color due to these elements. When the fluid turns from clear to a dark green or red, check its level and replace it immediately.

You may hear a chattering sound when your vehicle accelerates or takes turns around corners when low on transmission fluid. This could indicate an actual leak within the transmission itself.

Transmission fluid is used to lubricate and cool your vehicle’s gears as well as protect its internal components. It consists of synthetic base oils mixed with mineral additives that are blended together for specific performance requirements.

About Engine Oil

Transmission Fluid Vs Engine Oil

Engine oil and transmission fluid are both liquids that help protect your car’s internal components. But they each have distinct purposes and characteristics.

Engine oils, for instance, are composed of base oils that have been processed with various additives to create an ideal lubricant for your vehicle’s engine. These may include antiwear additives, detergents, viscosity-related additives and more.

Engine oil and transmission fluid can be distinguished by looking at their labels. The first part of the label displays an API service rating, which indicates that the oil meets or exceeds standards set forth by the American Petroleum Institute (API).

Another part of the label indicates the viscosity of the oil. For instance, 75W90 indicates that it is thicker than 10W40 motor oil.

Similar to engine oil, the Society of Automotive Engineers sets standards for transmission fluid viscosity. These levels are determined by several factors such as the amount of fluid used, its operating temperature, and bearing clearances.

Read Also: Top 10 Best Motor Oil Brands in the World

Transmission Fluid Vs. Engine Oil

Engine oil and transmission fluid are two distinct lubricants used in different areas of a car. Each has its own purpose, so it’s important to use them correctly for maximum performance from your car.

Motor lubricants are composed of synthetic or mineral base oils and additives that have been carefully blended by manufacturers to meet performance specifications. Manufacturers recommend changing them when levels become low or there are signs of contamination.

Motor oil typically contains high levels of detergents and anti-oxidants to safeguard the engine against wear-and-tear. Apart from that, they have extreme pressure or anti-wear additives similar to what would be found in standard ATF such as 7cSt in Timken Test.

Transmission fluid is a type of hydraulic liquid that transfers power from an engine to a gearbox. It lubricates the gears, keeping them from grinding against each other or stripping off.

Manual and automatic transmission fluids are both available on the market; however, the primary distinction between them is that automatic transmission fluid is designed for use at higher temperatures and pressures.

Automatic transmission fluid tends to deteriorate much more quickly than manual transmission fluid, so it’s essential to change it regularly in order to prevent issues with the gears. Doing so could reduce driving efficiency and even damage the transmission.

Can You Use Transmission Fluid Instead of Motor Oil

Engine oil

No matter the make or model of your vehicle, it’s essential to note that transmission fluid cannot substitute for motor oil. This is because they have distinct functions and components.

Not only that but they differ in viscosity levels and are intended for different functions. Engine oil serves the engine, while transmission fluid focuses on steering and gear systems of your car.

Both oils can make your car run efficiently and keep it lubricated. They also prevent it from getting overheated, which could damage parts.

However, there may be times when it’s necessary to mix these two types of oils together. This is especially true if you need to flush your engine for engine sludge.

When this occurs, you can mix about 1 quart of automatic transmission fluid with engine oil to more effectively remove sludge.

One potential drawback of this trick is that it may reduce your engine oil’s solvency and lubrication properties, so only do it if absolutely necessary.

If you do need to use this trick, be sure to adhere to your owner’s manual or mechanic’s recommendations.

Disposing of transmission fluid properly is important; not by pouring it into your engine oil or down the drain. Doing so could block your plumbing system and even start a fire. Furthermore, most recycling centers won’t accept transmission fluid if it has been mixed with other automotive fluids or has been contaminated.

Is Transmission Fluid Better Than Engine Oil?

There is no way to actually tell which is better since they both serve different purposes. Engine oil and transmission fluid are both lubricants that keep an automobile’s engine running optimally. However, they work differently and have distinct purposes.

Engine oils are essential in protecting an engine from wear and corrosion, while transmission fluid serves to provide power transmission between wheels of a car. Both these lubricants are composed of base oils plus additives that work together to enhance performance.

One major distinction between these two fluids is their viscosity levels. The thicker the lubricant, the easier it will flow between moving parts in your transmission and be able to withstand higher pressure levels.


As you can see, there are a huge difference between transmission fluid and engine oil as both of them serve different purposes. We don’t think it would be a good idea to use transmission fluid in your vehicle’s engine and it’s pretty much the same for engine oil, it should never be used in your vehicle’s transmission either.