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Discussion Starter · #1 · (Edited)
First, I have done plenty of research on this topic, but most threads were pre 2010, so I figured I would start a new thread for my situation. I have an 01 F350 7.3 with the 4R100 tranny, which was rebuilt with upgraded clutches and converter about 35k mikes ago in 2015. Its about time for a fluid change, but i dont know if they put Mercon or Mercon V in it, nor donai know if it was dino or synthetic. I dont want to do a chemical flush because of horror stories ive heard about it damaging transmissions, so i figured i would just do a full fluid and filter change including draining the converter. All the threads i read about the potential harm from using Mercon V, even after the supposed reformulation, were highly debatable and it seemed like 50% of people were for the switch to Mercon V and the other half were sticking with Dexron III/Mercon fluid. Last night, I made the decision to go with Dexron III/Mercon fluid, but now I am second guessing that because of the tranny rebuild. I guess my first question is, because the tranny has new clutches and converter, would I still be able to go with either Mercon fluid, or will it now need the Mercon V?And is it ok to mix the two, since i cant identify what is in it now? Also, since it has been rebuilt, would you recommend dino or synthetic?
 

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The specs are so close, to me, It comes down to three reasonable and user proven choices, the reformulated Motorcraft recommended Mercon V Synthetic, Valvoline MaxLife Synthetic or Mobil 1 Synthetic.
Just for a logic test, assuming that the three products were proven by users and equivalent what would most reasonable users choose.
They would, unless brand hypnotized, choose the cheapest of the three, and, use the $ difference to change more often. Net positive, cleaner the better.
One can easily DIY flush without chemicals and flush the entire system completely, there are many forum references to the flush process, it is very easy.
 

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Discussion Starter · #3 · (Edited)
If by flush, you mean using the rear tranny line to pump out additional fluid, that is exactly what i plan on doing. I didnt think it was considered a flush unless you use a chemical of some sort. Am I wrong? Is this method still considered a flush?
 

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If by flush, you mean using the rear tranny line to pump out additional fluid, that is exactly what i plan on doing. I didnt think it was considered a flush unless you use a chemical of some sort. Am I wrong? Is this method still considered a flush?
I think it's considered a flush.
 
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I think it's considered a flush.
It is - and in my opinion unnecessary unless you are flushing out a known contaminant - like the bozo at the quick change filled it with motor oil or something. The much easier way is to simply service the transmission more frequently. By dropping the pan, cleaning the magnet, periodically changing the filter - you effectively dilute the normal wear and tear contaminants and refresh the additive package. I personally service mine every third oil change (15K). I'm coming up on 285,000K on my original transmission and my pan is crystal clean every time. Like my Roll Tide buddy mentioned - Valvoline MaxLife is a great fluid and you can get it in the $17/gallon range at Walmart. I order about 8 gallons at a time. It takes 8 quarts to do the drop and drain.

Also, I suspect your new torque converter won't have a drain on it.
 
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I agree with RT and practice his method of every 3 oil changes draining the pan and refilling. In your case trans media and condition of the pan, were it me, I would drain the pan and remove it confirm that it has the correct filter element by installing a new filter and refill, about 7-8 quarts, the pan. Then, flush the system by the rear return line procedure. Note to get a full flush it must be mass warm won't work correctly below about 80F.
After doing this you will have established a known base line of materials and their installed condition and be able to make trend determinations at inspection downtime checkpoints
 

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Discussion Starter · #7 ·
It is - and in my opinion unnecessary unless you are flushing out a known contaminant - like the bozo at the quick change filled it with motor oil or something. The much easier way is to simply service the transmission more frequently. By dropping the pan, cleaning the magnet, periodically changing the filter - you effectively dilute the normal wear and tear contaminants and refresh the additive package. I personally service mine every third oil change (15K). I'm coming up on 285,000K on my original transmission and my pan is crystal clean every time. Like my Roll Tide buddy mentioned - Valvoline MaxLife is a great fluid and you can get it in the $17/gallon range at Walmart. I order about 8 gallons at a time. It takes 8 quarts to do the drop and drain.

Also, I suspect your new torque converter won't have a drain on it.
Damn I didnt think about the new torque converter not having the drain. I was hoping you would chime in RT, and I appreciate your input. My uncle just sold me the truck last year, and the tranny rebuild was done back in 2015. It has only been 40k miles, but i wanted to start fresh and get on top of all the maintenance. So i am assuming i would need to flush through the cooler line to drain the fluid in the torque converter right?
 

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Discussion Starter · #8 ·
I agree with RT and practice his method of every 3 oil changes draining the pan and refilling. In your case trans media and condition of the pan, were it me, I would drain the pan and remove it confirm that it has the correct filter element by installing a new filter and refill, about 7-8 quarts, the pan. Then, flush the system by the rear return line procedure. Note to get a full flush it must be mass warm won't work correctly below about 80F.
After doing this you will have established a known base line of materials and their installed condition and be able to make trend determinations at in downtown checkpoints
Just so i understand, drain and drop the pan, replace the filter, reboot pan and top off with 8 quarts. Then flush through the rear line? Wont that be draining the new 8 quarts i just put in?
 

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Just so i understand, drain and drop the pan, replace the filter, reboot pan and top off with 8 quarts. Then flush through the rear line? Wont that be draining the new 8 quarts i just put in?
No, that pan media is system upstream supply, the return line is system net downstream return. That first fill on upstream supply will push system media out the downstream return line into your catch pail. I would do that cycle at least 2 more times.
 

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Discussion Starter · #11 ·
No, that pan media is system upstream supply, the return line is system net downstream return. That first fill on upstream supply will push system media out the downstream return line into your catch pail. I would do that cycle at least 2 more times.
i gotcha, so after draining and dropping the pan, do NOT reinstall pan before refilling?
 

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You have to put your pan back on. I think what Oneof6 was saying is as you add new fluid- it will continue to cycle and push the old fluid out the return line. If your wanting to flush all the old fluid and change brands then follow Marks procedure.

The way RT does it, and if staying with the same A/T fluid that’s in there now you would only need to replace what you lost when you dropped the pan as you only have 40K on the rebuild.
Mark’s change procedure was helpful for someone like me who bought a truck with 185K and the A/T fluid smelled burnt, thus getting all or most all of it out. I replaced with Mobil 1 and have been very happy with it.
 

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i gotcha, so after draining and dropping the pan, do NOT reinstall pan before refilling?
One can't refill at all without the pan being installed.
 

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Discussion Starter · #14 ·
You have to put your pan back on. I think what Oneof6 was saying is as you add new fluid- it will continue to cycle and push the old fluid out the return line. If your wanting to flush all the old fluid and change brands then follow Marks procedure.

The way RT does it, and if staying with the same A/T fluid that’s in there now you would only need to replace what you lost when you dropped the pan as you only have 40K on the rebuild.
Mark’s change procedure was helpful for someone like me who bought a truck with 185K and the A/T fluid smelled burnt, thus getting all or most all of it out. I replaced with Mobil 1 and have been very happy with it.
yeah it only has 40k on it since the rebuild, but i thought 30k was the mileage to change fluid, so i am a bit over since it hasnt been changed since the rebuild
 

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Discussion Starter · #16 ·
You have to put your pan back on. I think what Oneof6 was saying is as you add new fluid- it will continue to cycle and push the old fluid out the return line. If your wanting to flush all the old fluid and change brands then follow Marks procedure.

The way RT does it, and if staying with the same A/T fluid that’s in there now you would only need to replace what you lost when you dropped the pan as you only have 40K on the rebuild.
Mark’s change procedure was helpful for someone like me who bought a truck with 185K and the A/T fluid smelled burnt, thus getting all or most all of it out. I replaced with Mobil 1 and have been very happy with it.
Plus, i dont know what fluid was used for the rebuild, so its not that i think its contaminated or anything, i just didnt want to mix fluids if that was a no no. Any input there?
 

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Discussion Starter · #17 ·
I agree with RT and practice his method of every 3 oil changes draining the pan and refilling. In your case trans media and condition of the pan, were it me, I would drain the pan and remove it confirm that it has the correct filter element by installing a new filter and refill, about 7-8 quarts, the pan. Then, flush the system by the rear return line procedure. Note to get a full flush it must be mass warm won't work correctly below about 80F.
After doing this you will have established a known base line of materials and their installed condition and be able to make trend determinations at inspection downtime checkpoints
This procedure would be just like the one that Mark posted a link to, except that in the procedure youare recommending, I will be dropping the pan each time before I flush through the return line, correct?
 

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No, you don't remove the pan each time. When you run the engine the pump will remove the fluid from the pan and put it into the transmission. Then you refill the pan and do it again.
 

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Discussion Starter · #19 ·
No, you don't remove the pan each time. When you run the engine the pump will remove the fluid from the pan and put it into the transmission. Then you refill the pan and do it again.
Ok, so just so i understand:

1. Drain pan
2. Drop pan, clean pan/magnet and replace filter
3. Reinstall pan and fill dipstick tube with 7 quarts
4. Disconnect return line fitting and connect clear hose
5. Start truck
6. While truck is idling and fluid is pumping, cycle through the gears, spending a few seconds in each gear before changing
7. Once you get 1.5 gallons of fluid in the bucket and see the big air bubble, kill the engine
8. Add 6 quarts to dipstick tube
9. Repeat steps 5-7.
10. Remove clear hose and reconnect return line
11. Add 6 final quarts to dipstick tube
12. Start truck, drive it and recheck fluid level, topping off if needed

Does that seem right Mark?
 

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That is right, but step 7 needs improvement.

It should say, "Watch for a large air bubble. It will occur around the 1.5 gallon mark. Shut the engine off when it appears." The air bubble is important, not that you reached 1.5 gallons.
 
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