Know What Happens If You Mix Mercon V And Mercon LV! Must-Know Facts

If you own a Ford vehicle, you would be well abreast with its two famous ATFs: Mercon V and Mercon LV. These two transmission fluids are not compatible with each other. But ever thought: what happens if you mix Mercon V and Mercon LV?

Mercon V and Mercon LV are two different automatic transmission fluids. Therefore, if you mix them, it simply takes your engine to an early grave. Shuddering and jerking are two of the common problems you may experience. Besides these, you will surely face more problems.

Therefore, be wise enough to listen to the manufacturers, and don’t mix the two. But you have mixed the two and now looking for some reasonable solution? Hehe, I caught you. Cheer up, fellow, and buckle down. The given article will blow by blow answer all your quizzings in detail!

Can You Mix Mercon V and Mercon LV?


Ford Motor Company recommends not mixing Mercon LV and Mercon V.

The reason is their different chemical formula and composition.

They contain different additives that aren’t compatible with each other.

Mixing them is not going to cause any explosion. However, it will affect your engine, decreasing its lifetime.

What happens if you mix Mercon V with Mercon LV?

If you mixed Mercon V and Mercon LV for either reason, you might not find any change or problem.

However, here are a few problems you might encounter sooner or later.

Trouble shifting gear

The first and foremost problem you might encounter is trouble shifting and changing gears.

The reason is poor lubrication. Since the two fluids aren’t compatible, they lower the lubricating properties.

Things could worsen if the two fluids combined result in slipping gears.

Engine may overheat

As the two fluids are kept from getting mixed, they can result in damage to the transmission and engine.

So, the chances of internal friction multiply, resulting in an overheated engine

Transmission failure

In the worst scenario, the mix-up can result in a disaster, i.e., transmission failure.

The engine will surge or idle whenever you try to power the car.

The reason is that the two incompatible fluids might have clogged the transmission filter.

Delay in Acceleration

If you notice that your automobile operates lingering, the mixed ratios have done their work.

The mixed ratio of fluids fails to produce the required hydraulic pressure. Thus, your car hesitates to reach full acceleration.

Production of weird noise

Another red flag you might run into is the production of strange grinding and clunking noise.

It clearly indicates that the mixed ratio of Mercon V and Mercon LV needs to be corrected.

Consequently, the components of the engine rub against one another, resulting in excessive friction.

Moreover, decreased lubrication can also grind away the gears. In short, it increases the chance of wear and tear.


Another possibility is that you might come across shuddering and jerking.

The reason is that although Mercon LV has exclusive anti-shudder protection, Mercon V doesn’t.

So, the mixed fluid has less anti-shudder properties than Mercon LV.

This results in noticeable jerking and shuddering, particularly in Ford, Lincoln, and Mercury vehicles, which recommends using Mercon LV.


Lastly, you might notice leakage of transmission fluid.

It is a clear indicator that your car’s transmission is damaged and you need to change the transmission fluid.

These are some of the possible red flags you will encounter sooner or later.

So, if you are lucky enough not to experience one, gear up and get your transmission fluid changed.

What to do if you mix Mercon V and Mercon LV? THE ULTIMATE SOLUTION!

Once you have mixed Mercon V and Mercon LV, you definitely can’t rewind the time or separate them.

So, keep your calm, as narrowed down are the two easy solutions to your problem.

Transmission Flush

The best solution to opt for is transmission flush. It flushes away all the old ATF present in the system.

Moreover, it removes any debris or contaminants that build up in the system.

It is done using a professional transmission flushing machine.

The flushing machine’s hoses are connected to the cooling lines of the car.

These hoses drain all the old fluid from the system and replenish it with new, compatible transmission fluid.

It is, however, costly and takes nearly two to three hours for the flushing process to complete.

But on the other hand, it makes sure to remove all the old fluid from each corner of the system.

Transmission Fluid Change

The second option that you can opt for is a transmission fluid change.

This method only drains the old transmission fluid and adds the new one.

But the downfall of this process is that some of the old Mercon LV and Mercon V mixture will be left behind.

It takes nearly half an hour to complete the transmission fluid change.

Why Should You Not Mix Mercon V With Mercon LV?

Ever thought about mixing tea and coffee? Both drinks work to get a shot of energy boost, then why not?

No one does!

Similarly, you can’t mix Mercon V with Mercon LV.

They are two different automatic transmission fluids with entirely different properties and specifications.

Mercon LV has a lower pour point and viscosity than Mercon V.

Similarly, the stable viscosity index of the latter helps it get an edge over Mercon LV.

Therefore, keeping aloof from mixing the two non-compatible oils is a wise and money-saving decision.

Instead, you can mix other ATF the manufacturers claim to be compatible with.

What is Mercon V compatible with?

Mercon V is compatible with the following fluids:

  • Type CJ
  • Type H
  • Dexron III

What is Mercon LV compatible with?

Mercon LV is compatible with the following transmission fluids:

  • SAE 20W fluid
  • ISO 46 hydraulic oils
  • Mercon SP

Frequently Asked Questions (FAQs)

Can I mix Mercon V with Dexron III?

You can mix Mercon V with Dexron III.
The reason is that these two transmission fluids have quite similar chemical compositions.
This makes the two fluids compatible.

Is it OK to mix different transmission fluids?

You can’t mix any transmission fluid. Else the transmission fluid mixture will fail to function correctly.
You should only mix two compatible transmission fluids.

When should you change the transmission fluid?

Most of the manufacturers recommend changing the following:
*Manual transmission fluid after covering 30,000 to 60,000 mileage
*Automatic transmission fluid after 60,000 to 100,000 mileage

Can you use any transmission fluid with any engine?

You can’t use any transmission fluid with any engine.
The type of transmission fluid depends on the engine type, model, and year of manufacture.

Final Verdict

To finish with, it is better to keep Mercon V and Mercon LV.

Mixing Mercon V with Mercon LV will result in lowered lubrication and increased friction.

Consequently, your automobile transmission will get damaged, the engine will heat up, and the gears will grind away.

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