Maintenance: Changing the PTU Fluid

Ironically, PTU fluid in my 2017 Ford Explorer Platinum is considered a lifetime fluid and does not need to be changed for the life of the vehicle. However, when researching, owners of the Explorer recommend changing the fluid every 30,000 miles. I came across a few posts where they mentioned that the fluid was black and sludgy when performing a drain and fill after 50,000 miles. With 55,000 miles on my PTU, I was worried that it may break down in the near future. I decided to change the fluid before my cross country trip. I am dividing the guide into two parts, draining the PTU and filling the PTU.

What I used?

• 1/4″ hex wrench to open the drain plug
• Permatex 59214 High Temperature Thread Sealant to prevent the drain plug from leaking fluid
• 75W-140 Gear Oil is the required fluid for the PTU
• Flat head screw driver to release the PTU vent hose fastener and to detach the plastic vent breather cap
• 5/16″ fuel hose to extend the PTU vent hose
• 5/16″ x 5/16″ brass hose fitting  to extend the PTU vent hose
• MixMizer Injector to help put fluid back into the PTU

Draining the PTU

Step 1. Elevate the car.

Simply lifting the front should be enough.

Step 2. Remove the lower shield.

There are 3 screws which can be loosened by hand.

Step 3. Locate the PTU drain plug.

The drain plug should be placed next to a catalytic converter and above an O2 sensor.

Step 4. Insert a 1/4″ hex wrench into the drain plug.

Luckily, I had a 1/4″ hex wrench in my toolbox. If you can’t find a 1/4″ hex wrench, you can use the bottom of a screw bit base as a substitute.

My drain plug was seized, so I had to make use of a gas pipe fitting on my hex wrench to gain more leverage. I was able to loosen the drain plug after.

Step 5. Let it drain.

I used the foil to guide the PTU fluid down. I was happy to see the fluid was bright yellow-brown and not black.

I’m glad I performed this maintenance at 55,000 miles. I wish the previous owner had changed it at 30,000 miles. The illustration above doesn’t accurately reflect how sparkly the fluid looked. But if you examine it closely, you can view specs of glitter.

At the tip of the drain plug there will be some metallic debris. Do not be surprised to see more of this debris stuck near the PTU’s drain hole.

14 Oz of fluid were drained.

Step 6. Put back the drain plug.

Once it’s done draining, I applied some Permatex 59214 High Temperature Thread Sealant along the drain plug and reinstalled it.

Step 7. Reinstall the lower shield.

There’s no need for me to be under my car anymore so I reinstalled the bottom shield in Step 1.

Filling the PTU

Ugh! I really struggled with this part for a good long while. I was planning on extending the PTU vent tube but I couldn’t pry the plastic vent tube cap from the top of the engine bay. So I then decided to disconnect the entire hose by tugging on it, but it wouldn’t budge either. However, by chance I discovered that it was much easier to lengthen the hose from underneath of the car.

Make sure you familiarize yourself with the location of the vent breather cap, so that you have an idea of what it looks like underneath the car.  The arrow in the picture above points to the location of the breather cap. 

It’s a small, round plastic cap that is well concealed.

Step 1. Disconnect the hose fastener from the engine block.

Here’s a far out picture of the fastener that holds the vent hose pipe. To access this area I had to go under the car and move under the front of the drive shaft.

A zoomed up picture of the fastener that holds the PTU vent hose. I used a flathead screw driver to pry it off. I was surprised by how effortlessly it came off.

Step 2. Remove the plastic vent breather cap.

I used a flat head screw driver to wiggle the plastic vent breather cap off from the hose. I inserted the flat head screw driver in between the rubber and the vent breather and slightly rotated my flat head screwdriver clock wise to push the vent breather out. Did that a few times around the vent breather and it eventually came out.

Step 3. Extend the hose.

Now that the hose is open. I inserted the 5/16″ x 5/16″ barb and connected 3′ of fuel line to complete the extension. After, I routed the extended fuel line to the engine bay.

Step 4. Filling the PTU

The easiest way to refill the PTU is to use this plastic syringe injector called the MixMizer injector.  Feel free to use anything that’s similar but this worked perfectly for me since it was easy to insert, fill, and then remove. 

Insert the syringe without the plunger.

Pour in 75W-140 gear oil. You will see the liquid level steadily decrease and then stop, quite possibly due to an air gap. To make things flow faster, I’ll force the liquid down by by using the syringe’s plunger.

Using this method I was able to push majority of the fluid down. However, when pulling the plunger upwards, around 20 percent of fluid will travel back. I did this around eight times.

Step 5. Reinstall the plastic vent hose breather cap and zip tie it down.

Wondering what happened to the top cap? I somehow lost the cap when attempting to pull it off. I spent a good hour looking for the cap but couldn’t find it.  I’ll be replacing it in the future but no rush in replacing it now since this will be under the engine cover. 

Once I verified 14oz has drained from the bottle, I installed the vent breather cap and zipped tied the hose to keep it secure.

Overall, changing fluid in my PTU made me miss the ease of maintaining a Nissan Xterra. The Explorer PTU does not feature a fill hole, depending on the year some don’t even come with drain holes. Luckily my 2017 Ford Explorer Platinum has one. I spent almost four hours on changing the PTU Fluid. For most of the time, I was trying to remove the vent hose breather cap. I’m sure if I were to start from the beginning with my current knowledge it’ll take me no more than 30 minutes. My next drain and fill should be even more simple because everything is already setup.  I’ll provide an update when I do! 

Maintaining the PTU Fluid Update

As promised, I’ll provide an update on my PTU maintenance. I currently have reached 30,000 miles (85,000 miles on my odometer), which means it’s time to drain and fill the PTU fluid.

The process was a lot easier. I’ll admit I did make a bit more mess when draining since my drain “slide” wasn’t as well made as last time. But overall, it was almost as easy as changing an engine oil (some days are messier than others). I was able to drain and catch 14 oz. It was a windy day so some flew onto the side of the oil pan so I added around 16 oz this time. 

What the plug looks like.

The fluid still had some glitter to it, it’s possible we’re seeing some remnant of the original factory fluid since I did not previously do a full flush. We will see if the next fluid change is less sparkly.

In conclusion, I’m feeling excited to have completed my 2nd drain and fill of the PTU. I’m really hoping this will help extend its lifespan, so I’d love to hear from you if you’ve had similar experiences! Your tips and tricks are always welcome, as well as any words of advice. It’s great to know there is a community of people out there willing to help each other out and keep our vehicles running smoothly for years to come.