Transmission fluid drain & refill at 10K miles - results for 2025 LOBO EcoBoost

[BK007]

This is not the same transmission you've had 50+ years of experience with.

Since the filter can't be changed in the 8F35 transmission without removing it from the vehicle and splitting the case open, it is highly encouraged that you not perform a flush, but rather do frequent drain & fills only. Flushing the transmission can stir up settled contaminates and force those contaminates into the non-replaceable filter and solenoids. If you want to do a more thorough replacement of fluid, it is recommended that you do 3 drain & fills consecutively with short running cycles in-between.

This is a good article to read to understand the unique challenges of maintaining, rebuilding the 8F35 and it's failure modes: https://transmissionaudit.com/units/ford-transmissions/8f35/ Take note of the "Checking the Fluid", "Maintenance :Ignore the manual" and "FAQ" sections of the article and the recommendations there.

This is not the only source of these recommendations. There are other Ford certified transmission techs who have made the same or similar recommendations. The article above is concise in summarizing all of the information in one place.

That is a great site!! Thanks for posting it! https://transmissionaudit.com/units/ford-transmissions/8f35/

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[Darryl]

What frequency do you think is good for the hybrid transmission? I'm at 35k and plan at doing at 40k

If you don't do much towing I'd say 60,000 just for peace of mind. But personally I'm not changing mine until around 80-90 k . Even then it'll be because that's just before the Hybrid transmission warranty expires. The Hybrid transmission doesn't have any moving parts other than the planetary gear and bearings. No clutches to generate contaminates. The Hybrid fluid stays clean . And unless towing there's no excessive heat

 

[BK007]

I was really starting to get nervous, it's been 2 days now since the last oil change post.

One can never be too careful. Good job, OP!

@Bob The Builder Careful Butch, you almost had to go 48 hours without a fluid debate!

Man, it's wild how a simple "what do you guys do?" thread turns into a full-blown aerospace engineering conference overnight. And I say this as someone who is 100% guilty of losing sleep and overthinking my own fluid intervals too!

Like I said earlier, I just do what works for my own garage. At this rate, we're gonna need a group therapist for the 8F35 and eCVT transmissions by page 5!

 

[HeyBales]

@Bob The Builder Careful Butch, you almost had to go 48 hours without a fluid debate!

Man, it's wild how a simple "what do you guys do?" thread turns into a full-blown aerospace engineering conference overnight. And I say this as someone who is 100% guilty of losing sleep and overthinking my own fluid intervals too!

Like I said earlier, I just do what works for my own garage. At this rate, we're gonna need a group therapist for the 8F35 and eCVT transmissions by page 5!

Na.
The eCVT guys the info is just spinning around our head.
The 8F35 guys the info is just grabbing their attention.
The Lobo guys are missing a bit.

Eh, eh?

 

[BlueMaverick23]

I actually just did an order on RA today for engine oil, filters, gear oil, etc for the 50k mile service for my truck. It did let me buy with ULV in the cart so hopefully I will get it.

Just would like to know is this your first transmission service at 50k, I have 39,000 on my 23 ecoboost just for a rule of reference, I going to do mine at 50k also

 

[matmondro]

Just would like to know is this your first transmission service at 50k, I have 39,000 on my 23 ecoboost just for a rule of reference, I going to do mine at 50k also

This will actually be my second transmission service. My first was at 25k miles and I plan to keep doing them every 25k miles.

 

[ListedGuru]

If you don't do much towing I'd say 60,000 just for peace of mind. But personally I'm not changing mine until around 80-90 k . Even then it'll be because that's just before the Hybrid transmission warranty expires. The Hybrid transmission doesn't have any moving parts other than the planetary gear and bearings. No clutches to generate contaminates. The Hybrid fluid stays clean . And unless towing there's no excessive heat

What are you thoughts on when to change the RDU and PDU fluids in the AWD Hybrid Mavs?

 

[Darryl]

What are you thoughts on when to change the RDU and PDU fluids in the AWD Hybrid Mavs?

Ford says filled for life unless operated under severe service such as towing and a lot of off road conditions. I don't recommend that. Personally I'd probably change it around 80,000-90,000 under normal conditions and around 60,000 for severe service. I wouldn't change it nearly as often as some on this forum. That's overkill. But 60,000 should be plenty under severe service conditions

 

[DannyDread]

I just drained and refilled my 2023 XLT. Something that I see being done incorrectly in all the YT videos and stated in other comments in forums concerning the filler tube. You're supposed to remove the entire breather tube per the 2022 Maverick service manual that is posted elsewhere on this site. You remove it via the spring hose clamps. The service manual clearly shows this below. Don't try to pour fluid into the rubber breather tube, there is a small plastic disc in there with a hole the size of a nail. That's why it takes so long to fill that way, and it's the wrong way of filling it.

BTW, this looks like an AI generated site. Non-vetted info there, definitely not written by a human.
https://transmissionaudit.com/units/ford-transmissions/8f35/

 

[ListedGuru]

Ford says filled for life unless operated under severe service such as towing and a lot of off road conditions. I don't recommend that. Personally I'd probably change it around 80,000-90,000 under normal conditions and around 60,000 for severe service. I wouldn't change it nearly as often as some on this forum. That's overkill. But 60,000 should be plenty under severe service conditions

Thanks for the input. So I assume the PDU and RDU are just drain and fills like the ecvt should be correct?

 

[BK007]

Thanks for the input. So I assume the PDU and RDU are just drain and fills like the ecvt should be correct?

Front PTU:

• Spec: Motorcraft SAE 75W-85 Premium Synthetic Hypoid - XY75W85QL
  
  
  
• Capacity: ~0.4 - 0.5 Quarts (12.7 fl oz).

Rear RDU :

• Spec: MOTORCRAFT XY75WQL SAE 75W Disconnect Rear Drive Unit Fluid
  
  
  
• Capacity: ~0.9 Quarts (28 fl oz).

 

[Darryl]

Ford says filled for life unless operated under severe service such as towing and a lot of off road conditions. I don't recommend that. Personally I'd probably change it around 80,000-90,000 under normal conditions and around 60,000 for severe service. I wouldn't change it nearly as often as some on this forum. That's overkill. But 60,000 should be plenty under severe service conditions

Thanks for the input. So I assume the PDU and RDU are just drain and fills like the ecvt should be correct?

Yes just drain and fill

 

[kiljander]

I changed my transmission fluid at 30,000 on my 23 tremor and the fluid was pretty dark -no metal. I changed it twice. 9qt capacity but you can only drain 4 1/2 qts, ran it for 500 miles and changed it again, Looks fairly good now! Also changed my PTU and RDU but they looked like new.

 

[matmondro]

I just drained and refilled my 2023 XLT. Something that I see being done incorrectly in all the YT videos and stated in other comments in forums concerning the filler tube. You're supposed to remove the entire breather tube per the 2022 Maverick service manual that is posted elsewhere on this site. You remove it via the spring hose clamps. The service manual clearly shows this below. Don't try to pour fluid into the rubber breather tube, there is a small plastic disc in there with a hole the size of a nail. That's why it takes so long to fill that way, and it's the wrong way of filling it.

BTW, this looks like an AI generated site. Non-vetted info there, definitely not written by a human.
https://transmissionaudit.com/units/ford-transmissions/8f35/

Correct. I documented this in a thread here on MTC almost two years ago when I did my first transmission service. It was an absolute joke trying to fill through the tube. Removal of the entire tube is necessary for this job.

 

[matmondro]

I actually just did an order on RA today for engine oil, filters, gear oil, etc for the 50k mile service for my truck. It did let me buy with ULV in the cart so hopefully I will get it.

To follow up, Rockauto did indeed have that liquid gold in stock

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