As an automotive specialist with years of experience in the industry, I can share some insights on what happens when oil is put into the transmission. It's important to understand that transmissions and engines require different types of fluids for optimal performance. The fluids are designed to meet the specific needs of each system, and using the wrong fluid can lead to serious problems.

Step 1: Initial Reaction

When you put oil in the transmission, the first thing that happens is that the oil may not be compatible with the transmission's components. Engine oil and transmission fluid have different viscosities and additives. Engine oil is designed to lubricate, cool, and clean the engine's internal parts, while transmission fluid is formulated to handle the unique demands of the transmission, such as clutch engagement and gear shifting.

Step 2: Potential Issues

If the engine is not run after adding engine oil to the transmission, the immediate effects might not be apparent. However, if the vehicle is driven, several issues can arise:


1. Clutch Slippage: The incorrect viscosity of engine oil can cause the clutches within the transmission not to engage properly, leading to slippage and reduced power transfer.


2. Gear Wear: The additives in engine oil are not designed for the friction characteristics required in a transmission. This can accelerate the wear on gears and other internal components.


3. Heat Build-up: Transmission fluid is specifically formulated to handle the heat generated by the transmission. Engine oil may not dissipate heat as effectively, leading to overheating.


4. Seal Degradation: The chemical composition of engine oil can cause the seals within the transmission to degrade over time, leading to leaks.


5. Shifting Problems: The incorrect fluid can affect the transmission's ability to shift gears smoothly, resulting in harsh or erratic shifts.

Step 3: Long-Term Consequences

Over time, using engine oil in the transmission can lead to more severe issues:


1. Total System Failure: Prolonged use of the wrong fluid can cause complete transmission failure, necessitating a costly repair or replacement.


2. Loss of Vehicle Performance: As the transmission deteriorates, the vehicle's performance will suffer, becoming less efficient and reliable.


3. Increased Maintenance Costs: The need for more frequent repairs and replacements of parts can significantly increase the long-term maintenance costs of the vehicle.

Step 4: Corrective Measures

If engine oil has been mistakenly put into the transmission, it's crucial to take immediate action:


1. Drain the Fluid: As soon as possible, drain the engine oil from the transmission to prevent further damage.


2. Flush the System: Perform a thorough flush of the transmission to remove all traces of the incorrect fluid.


3. Refill with Correct Fluid: After flushing, refill the transmission with the correct type of transmission fluid as specified by the vehicle's manufacturer.


4. Monitor the Vehicle: Keep a close eye on the vehicle's performance and be prepared for potential transmission issues that may arise.

In conclusion, while putting engine oil in the transmission may not cause immediate catastrophic failure, it can lead to a series of problems that will affect the transmission's performance and longevity. It's always best to use the correct fluids as specified for each system to ensure the vehicle operates safely and efficiently.

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If after you did this, you did NOT run the engine (thus operating the torque converter and oil pump in the transmission), nothing untoward will happen. ... Putting engine oil in the transmission is not as bad as putting "oil" in a hydraulic brake system. If that happens, much of the brake system has to be rebuilt.Jan 13, 2017read more >>