Can I Use Motor Oil in Transmission? | Technical Guide

Generally, people ask can I use motor oil in transmission? Motor oil and transmission fluid have different formulas, and the misapplication can cause damage to the engine.

Are you wondering whether lu or transmission fluid are the same? Generally, people think engine lubricant and transmission fluid are the same. However, they serve a different purpose. Transmission fluid lubricates gears to increase their performance and speed. Motor oil is automobile engine lube that works with combustion products in the engine.

The car mechanism is not that simple. There are different types of oil used in the running of the engine. Generally, people confuse motor oil and transmission fluid. Misapplication of these fluids can cause damage to the engine.

In this article, I will answer a question like, can I use motor oil for transmission fluid? Before starting with the answer, let’s discuss the difference between engine liquid and automatic transmission fluid.

use motor oil in transmission

Transmission oil vs Engine oil

Engine oil improves sealing and prevents rust in the mechanical parts of the engine. Moreover, engine oil reduces friction and cools down the engine system. Engine lube improves the efficiency and effectiveness of the components that are in the combustion chamber. On the other hand, transmission fluid enhances the operation of the car. Mainly transmission fluid lubricates the steering system and transmission system. It improves the functions of the clutch and gears. Let us discuss the difference between these fluids in detail.

1. Function

Engine lubricant is the oil that lubricates the internal parts of the combustion engine. It makes the engine sludge-free and reduces friction between the moving parts. However, Transmission liquid greases internal components of the car transmission system and dissipates heat. It improves the performance of the steering and gear system.

2. Consumption Rate

The liquid improves the efficiency of the car. It reduces time and mileage. On the other hand, transmission oil doesn’t affect time and mileage.

3. Color 

The original color of lubricant is amber. However, it turns darker with usage. If the color turns cloudy, it indicates contaminants. On the other hand, transmission fluid colors range from red to green.

Motor oil has a high viscosity, and it works better in high temperatures and pressure. However, transmission fluid has low density because it operates under low pressure and temperature. Generally, lubricant is changed after 3000 to 6000 miles because it loses its property. Transmission fluid doesn’t regularly need to be changed timely. You can change after 2 years.

4. Purpose

Motor oil’s prominent role is protecting engine parts against rust and improve sealing. Moreover, it also maintains engine oil and avoids coolant leaks. The ATF (automatic transmission fluid) lubricates the gear, clutches, and steer and improves operation. Moreover, it reduces corrosion and rust and improves the performance of the car.

What Happens if You Put Motor Oil in Transmission?

If you accidentally put oil in the transmission fluid, you will notice adverse effects. It can even damage the engine. However, damage depends upon how long the car is driven with the wrong fluid. Let’s look at the harms of oil in the transmission.

1. Delay Gears function

When a transmission system has motor oil instead of transmission fluid, gear will not function properly. Car gear will show signs of delay while driving. This is because the properties of transmission liquid are different from motor oil.

2. Gears slipping

Another issue you might face is Gears slipping. Gear slipping can cause a severe accident, and it’s a safety concern. Transmission fluid helps in gears shifts. It allows the car to move in forward and reverse direction. However, motor oil cannot perform this function.

3. Gear doesn’t work smoothly

The ATF system helps the gear system to work effectively. It lubricates small parts like O-rings and seals. You will feel that the gear is not functioning accurately when the engine oil is used instead of transmission fluid. Moreover, you might experience a grinding sensation when changing the gear. This is because parts of the gear are not working correctly.

4. Burning like smell

The burning smell from the car is not a good sign. Generally, transmission fluid has high lubricating properties and reduces friction between different parts. However, replacement of transmission fluid with another lubricant. Friction between parts can cause heat resulting in a burning smell. If the problem exists, this can lead to a total collapse of a transmission system. You may notice blue smoke from exhaust if more oil leaks in the system.

5. Noise while driving

When the transmission system is not well lubricated. It will generate different sounds when driving. This is because different parts collide with each other.

What happens if you put transmission fluid in your oil? 

People ask can you mix transmission fluid with engine oil? The answer is no. Every oil has a different purpose, and mixing can cause damage to the engine. Let’s look at what happens if you put transmission fluid in your oil.

1. Reduces Cleaning power

Generally, lubes have detergent in them. Detergents perform two essential functions. They clean the metal part in the engine. A small amount of detergent removes sludge. Secondly, as they are alkaline they neutralize the acidic effect. Generally, ATF has a large quantity of detergent than Engine oil. If you add ATF in engine oil, it will not work as effectively. Motor oil and Automatic Transmission Fluid are different. Lubricants work with combustion byproducts. So detergent level is low. If CVT fluid is in oil, it decreases the cleaning power. Furthermore, ATF has a high level of friction minimizer that safeguards clutches and gears. These qualities are not of an engine flush.

2. Doesn’t work in High temperature

Generally, viscosity is an important factor. Change in viscosity causes harmful effects on the engine. An increase in viscosity causes a machine to overheat. However, a decrease in viscosity doesn’t lubricate the machinery properly. ATF has low viscosity; it doesn’t work in high temperatures and pressure.

3. Change oil formation

Engine oil formulation is different from transmission oil. Change in formulation reduces effectiveness. Moreover, an engine is a perfect blend of base oil and additive. It lubricates the engine components, reduces friction, and makes the engine sludge free. Adding ATF in the engine causes adverse effects and can cause white exhaust smoke with wear and tear. ATF also decreases wear protection, and can cause permanent damage.

 Substitute for transmission fluid

The substitute for transmission fluid is not motor oil. Generally, CVT oil has an additive formulation. Replacement of the transmission fluid should have more addictive properties than lubricant ones, which help them to performs these four major functions.

  1. Cleans the contaminants
  2. Lubricate moving parts
  3. Cooldown the transition system
  4. Protect gears against rust and corrosion

The substitute for ATF is manual transmission fluid or gear oil. Gear liquid lubricates and protect gear and transmission system from wear and tear. However, CVT liquid is not a perfect solution because it doesn’t have an ideal number of additives to run the transmission system. Still, it’s a better solution than motor oil. Lube can lead to transmission failure and can cause damage to the clutch and gear system of the car. Hope you have got clear idea regarding transmission fluid vs motor oil.

FAQ (frequently asked questions)

1. Is it bad to put motor oil in your transmission?

Yes, using motor oil in your transmission system can lead to transmission failure. Moreover, it can cause overheating, reduce lubrication, leading to wear and tear of clutches and gear. It can also damage many small components like O-rings and seals. If the transmission failure occurs, it’s difficult for a mechanic to reverse the effects.

2. What can be used in place of transmission fluid?

Transmission fluid is specially designed for the transmission system. It has an ideal number of additives to run the system. However, if you are looking for an alternative, manual transmission fluid and CVT fluid are the best options. Gear oil has the right amount of viscosity, and it improves performance.

3. Does oil go through the transmission?

No, engine lubricant and transmission have different functions. The engine oil that interacts with frictional parts. However, transmission fluid lubricates and protects gears and clutches in a transmission system. Engine lube doesn’t go through the transmission system.

oil in transmission

4. Will motor oil work in a transmission?

Engine oil has different compositions and viscosity than CVT fluid. Motor oil can cause damage to the steering and gear system. Moreover, it can cause transmission failure. Lube is not a substitute for wrong fluid.


Generally, people think that engine and transmission oil are the same. However, they are different and have different purposes. People ask can I use motor oil in transmission? The answer is No. Transmission fluid (ATF) has fewer lubrication properties and more additives. It lubricates and protects the transmission and steering system. Moreover, it cools down the system and improves its efficiency.

On the other hand, motor fluid that lubricates parts of the combustion engine. It has a high viscosity that helps it work in high temperatures and pressure. If transmission fluids and motor oil get mixed, it can cause damage to the engine or result in transmission failure.


Mr. Rubel is an Engine Mechanic. He has more than 15 years’ experience on repair and maintenance of different kinds of vehicles. He is also providing training to mechanics and works as a Senior Mechanic of a well-known organization. He is sharing his knowledge to support the car lovers to solve the vehicle issues.

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