Transmission Fluid Change Theory

[Maverick Country Club]

My calculations are pushing me to strongly considering draining the 4 to 4.5 quarts that is easily removed from the drain plug and replacing the exact amount of fluid when changing the oil every 10k instead of 3 to 4 simultaneous drain and fills at one time at 30k. The same amount of fluid cost either way.

Legend: Average Miles on Fluid Mixture
Half 1X/10k Method
0k=0k
10k=(50%10k+50%0k)=5k
20k=(50%15k+50%0k)=7.5k
30k=(50%17.5k+50%0k)=8.75k
40k=(50%18.75k+50%0k)=9.325k
50k=(50%19.325k+50%0k)=9.6625k
60k=(50%19.6625k+50%0k)=9.83125k
70k=(50%19.83125k+50%0k)=9.91562k
80k=(50%19.91562k+50%0k)=9.95781k
90k=(50%19.95781k+50%0k)=9.97891k
100k=(50%19.97891+50%0k)=9.98945k
110k=(50%19.98945k+50%0k)=9.99473k
120k=(50%19.99473k+50%0k)=9.99736k
130k=(50%19.99736k+50%0k)=9.99868k
140k=(50%19.99868+50%0k)=9.99934k
150k=(50%19.99934k+50%0k)=9.99967k
160k=(50%19.99967k+50%0k)=9.99984k
170k=(50%19.99984k+50%0k)=9.99992k
180k=(50%19.99992k+50%0k)=9.99996k
190k=(50%19.99996k+50%0k)=9.99998k
200k=(50%19.99998k+50%0k)=9.99999k

Legend: Average Miles on Fluid Mixture
Half 3X/30k Method
0k=0k
10k=10k
20k=20k
30k=(50%30k+50%0k=15k; 50%15k+50%0k=7.5k; 50%7.5k+50%0k)=3.75k
40k=13.75k
50k=23.75k
60k=(50%33.75k+50%0k=16.875k; 16.875k+50%0k=8.4375k; 50%8.4375k+50%0k)=4.21875k
70k=14.21875k
80k=24.21875k
90k=(50%34.21875k+50%0k=17.1094k; 17.1094k+50%0k=8.55469k; 50%8.55469k+50%0k)=4.27734k
100k=14.27734k
110k=24.27734k
120k=(50%34.27734k+50%0k=17.1387k; 17.1387k+50%0k=8.56934k; 50%8.56934k+50%0k)=4.28467k
130k=14.28467k
140k=24.28467k
150k=(50%34.28467k+50%0k=17.1423k; 17.1423k+50%0k=8.57117k; 50%8.57117k+50%0k)=4.28558k
160k=14.28558k
170k=24.28558k
180k=(50%34.28558k+50%0k=17.1428k; 17.1428k+50%0k=8.5714k; 50%8.5714k+50%0k)=4.2857k
190k=14.2857k
200k=24.2857k

I am thinking that a consistent 10k old fluid is better than 4k to 14k to 24k old fluid.

I will clarify what each part of my 50k calculation represents…

50k=(50%19.325k+50%0k)=9.6625k
The odometer reading is 50k when I remove the drain plug and only half of the fluid will drain. The other half will not drain as it is trapped in the torque converter.

(50%19.325k+50%0k)=9.6625k
This 50% represents the amount of used oil remaining in the transmission that will not drain as it is trapped in the torque converter.)

50k=(50%19.325k+50%0k)=9.6625k
The 19.325k represents the average mileage of wear on the fluid that won’t drain, which is a calculation of pervious changes every 10k.

(50%19.325k+50%0k)=9.6625k
This 50% represents the new fluid that I will use to replace what was drained.

(50%19.325k+50%0k)=9.6625k
This 0k indicates the new fluid has 0 miles of use.

(50%19.325k+50%0k)=9.6625k
This 9.6625k represents the average mileage of wear of the fluid mixture of 50% fluid with 19.325k of use and 50% of new fluid with 0 miles use.

I hope this better explains what I am thinking, so it is easier to interpret the equation. Thank you for your interest, and if I can explain this better, the findings when understood are interesting to me and possibly reveal this method to be a better choice than the videos that tell us to drain, fill then drain again then fill, then drain again and fill at 30k.
Also, this theory is irrelevant if you flush the transmission, but I am not comfortable with that as I had to rebuild a transmission after getting a scheduled 50k flush years ago. I don’t trust the flush process or the people doing it.

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[Maverick2022XL]

I think you are overthinking it. Change it when the color and consistency starts looking off.

 

[Ianrmcdonald84]

Former ford tech here. Do it every 30k. If you want be crazy/paranoid/spend money, do it more often. The older, but modern transmissions that asked for 30k fluid changes (look up definitions of normal service, no where meets it). Those were the heavy beat them up and they still lasted 200k+. But to reduce cost of ownership, amongst other reasons, they are basically full for life of maybe 150k.

I'll use my brother's 230k fusion still on original engine, transmission, ptu, rear diff. Change fluid. Never believe crazy intervals.

Also, ford lv and slv fluids are a bit darker naturally than good old mercon 5.

 

[Maverick Country Club]

I think you are overthinking it. Change it when the color and consistency starts looking off.

Hi Maverick2022XL,

Thank you for replying to my post. Yes, I agree, many would say I am 100% overthinking it. It is a hobby of mine to analyze and I enjoy mathematics. My form of crossword puzzle, it keeps my mind sharp or at least less dull and I come out of it with some relative information. There isn’t a dipstick or sight glass to check the fluid for consistency or fluid color, I could loosen the drain plug and let a few drops out but if I’m that far into it, I would just drain it and refill. Please share how you do/plan to service your transmission fluid, I’m interested. Again thank you, I appreciate your input.

Best regards,
Larry

 

[Ianrmcdonald84]

Honestly, 30k. Drain and fill. But keep in mind its not going to be bright red like old school mercon v.

 

[Ianrmcdonald84]

I'm also not towing anything. If you're towing, definitely 30k!

My buddy has two chevy 1500s and trailers...if i need to borrow a trailer, I'll grab his truck too and throw a few gallons of gas in it. Most I'll move with maverick is honestly 2000 ish. Lawn trailer plus small rider?

 

[dhaskit]

It’s your truck. You change it when you want to. Whatever makes you feel happy.

For me:
After the initial change at 5k miles to get the contaminants out, then;
I will change mine ‘on condition’ or just before Ford recommends it.
I bet my tranny lasts as long as your’s does in the end.

But again, you should service your machine in whatever way that gives you confidence in it’s longevity. You may, perhaps, be more knowledgable than Ford’s large team of Design and Test Engineers. Who’s to say.
At the very least, thank you for posting your premise. It was a fun read.

 

[Ianrmcdonald84]

Changing oil too soon is cheap insurance. Honestly I put 4k a year on my maverick. I live close to work. I drive maybe 30 miles down the interstate to the next town once a week. Otherwise it's heated garage kept. But I keep my vehicles forever.

 

[Maverick Country Club]

Former ford tech here. Do it every 30k. If you want be crazy/paranoid/spend money, do it more often. The older, but modern transmissions that asked for 30k fluid changes (look up definitions of normal service, no where meets it). Those were the heavy beat them up and they still lasted 200k+. But to reduce cost of ownership, amongst other reasons, they are basically full for life of maybe 150k.

I'll use my brother's 230k fusion still on original engine, transmission, ptu, rear diff. Change fluid. Never believe crazy intervals.

Also, ford lv and slv fluids are a bit darker naturally than good old mercon 5.

Hi Ian,
Thank you for replying to my post. Agree 100% on changing the other fluids. Regarding the cost… I am doing the work myself and the same amount of fluid is used either way. Regarding crazy paranoid… My incentive isn’t to be crazy or satisfy paranoia, I was thinking that while you had the underbody panel removed when changing the oil, the transmission fluid drain plug is right there. it would be easy to drain and refill but equally important is the consistently clean (10k age fluid) fluid compared to the initially 4k clean to 24k dirty roller coaster 30k method. Flushing the fluid would be ideal for clean fluid but rumor has it that flushing causes problems with debris effecting solenoids, which this transmission is rumored to have issues with. Hmmmm maybe that is the paranoia you are talking about. Again thank you, I appreciate your thoughts and input. I would be interested to know your thoughts on flushing the fluid?
Best regards,
Larry

 

[Tim d]

To bad Ford didn't use lifetime fluid like our dodge caravan. 16 years old and 181,000 miles and trans shifts like new.

 

[Ianrmcdonald84]

So most modern flush machines first use snake oil, that's how dealers get machines for free, just use our fluid....etc.

Let's assume that's not the case. They're a take and give machine. Unless something goes wrong, if the used jug adds 5-6quarts, the new jug takes the same out. Unhook, reconnect the easiest fitting that you tapped the machine into. Loose a tiny bit. There's no dipstick. And trust me, no one is pulling the fill plug to look.

X time is the devil. You have to recommend services or you'll get written up. I left the industry as a senior master gasoline tech.

 

[Maverick Country Club]

It’s your truck. You change it when you want to. Whatever makes you feel happy.

For me:
After the initial change at 5k miles to get the contaminants out, then;
I will change mine ‘on condition’ or just before Ford recommends it.
I bet my tranny lasts as long as your’s does in the end.

But again, you should service your machine in whatever way that gives you confidence in it’s longevity. You may, perhaps, be more knowledgable than Ford’s large team of Design and Test Engineers. Who’s to say.
At the very least, thank you for posting your premise. It was a fun read.

Hi Dann,
Yes, I have heard the initial fluid change is very dirty and should be done sooner than specified. Hopefully when one of transmissions go, we are still here to discuss it. “Who’s to say” is right, well put, but I question what is motivating their numbers, my best interest, or theirs. I’m glad you enjoyed it and appreciate your reply.
Best regards,
Larry

 

[Maverick2022XL]

Hi Maverick2022XL,

Thank you for replying to my post. Yes, I agree, many would say I am 100% overthinking it. It is a hobby of mine to analyze and I enjoy mathematics. My form of crossword puzzle, it keeps my mind sharp or at least less dull and I come out of it with some relative information. There isn’t a dipstick or sight glass to check the fluid for consistency or fluid color, I could loosen the drain plug and let a few drops out but if I’m that far into it, I would just drain it and refill. Please share how you do/plan to service your transmission fluid, I’m interested. Again thank you, I appreciate your input.

Best regards,
Larry

https://www.mavericktruckclub.com/f...th-torque-specs-per-the-service-manual.34319/

If you want to spin your wheels go prove 1 + 1 = 2. It took Bertrand Russell and Alfred Whitehead only 362 pages to do so in their book Principia Mathematica. Another case in point of over thinking things. I can prove that in 30 seconds with a dog and 2 doggie treats.

 

[Maverick2022XL]

Changing oil too soon is cheap insurance. Honestly I put 4k a year on my maverick. I live close to work. I drive maybe 30 miles down the interstate to the next town once a week. Otherwise it's heated garage kept. But I keep my vehicles forever.

Not really having to pay an extra $20 to check the fluid every 30k during a multipoint inspection is even cheaper than spending $200 per flush.

 

[Maverick Country Club]

I'm also not towing anything. If you're towing, definitely 30k!
My buddy has two chevy 1500s and trailers...if i need to borrow a trailer, I'll grab his truck too and throw a few gallons of gas in it. Most I'll move with maverick is honestly 2000 ish. Lawn trailer plus small rider?

Hi Ian,

I plan to tow my single Wave Runner/trailer that I use to troll for Salmon on the Great Lakes and a small enclosed snowmobile/trailer for ice fishing trips. The waverunner should be easy towing and I can’t wait to use the backup assist at the boat ramp. The snowmobile trailer on the other hand is more of a challenge with wind resistance as an added barrier. I plan to go slow although in the past my excitement to reach my fishing spot has caused my truck to leave the ground before. I purchased a 2k diesel heater that I plan to use when I sleep in the cab on fishing trips.

Best regards,
Larry

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