4R100 Filter Change
 

Hi guys. New to me 7.3 and I’ve changed all the fluids so far besides T Case and Transmission. I know for the TCase theyre not too picky and I dont do heavy towing so I was going to put in Mobil 1 synthetic ATF meeting the Mercon LV spec.

for the transmission, I bought a new filter for it. I am hesitant to do a flush of the system. My plan right now is to drain and drop the pan, change the filter, and fill back up with AMSOIL multi vehicle synthetic atf (red label). I don’t have a clue what brand atf is in there now, but that shouldn’t matter much if both fluids are compatible and meet mercon V spec?

Sounds like a good plan. The filter is not really critical, but if you find junk in the pan you'll be glad to have one ready to go. Got the 4wd filter?

I had a bad over temp when towing and burnt the fluid brown, with a bonus of bass boat golden glitter. Did exactly as you are planning plus a valve body and a 6.0 cooler. She lived just fine for years. But at the PM interval I paid the $tealership to do a full flush. Prolly overkill but it made me feel good.

The transfer case has a history of exploding with incorrect fluids, was a bit of fear porn for a few years. But yes, as long as the fluid meets the correct spec you're golden.

yeah i bought from riffraff who I believe only sells the 4wd filter. Got a new gasket too just bc it wasn’t expensive. The mishimoto trans cooler is on clearance right now at $227 so planning to get it.

What fluid did you put in t case? I usually swear by mobil 1. I thought about just using it for 4r100 too

Mercon LV is not compatible with Mercon V, nor is it compatible with original Mercon, now discontinued.

A transmission fluid cannot meet Mercon LV and Mercon V at the same time. The two standards are incompatible with each other, by definition of their respective fluid specifications.

If a so-called multi-vehicle ATF, even if synthetic, is advertised as suitable for use in vehicle applications calling for Mercon LV as well as Mercon V, I would avoid using that fluid.

Mobil 1 Synthetic LV ATF HP is NOT compatible with the transfer case, not is it compatible with the 4R100 transmission. I would avoid using Mobil 1 Synthetic LV ATF in either gear box.

However, Mobil 1 Synthetic ATF (a different product, without the "LV" in the name} is ok to use in both the transmission and the transfer case.

got it- so current recommendation is to avoid LV in both. This topic has gotten so confusing over the years…

IKR? Like just let Mercon die and call the next formula Fred and the next one after that Xavier. Create some clarity.

hahah yeah Ford should switch to hurricane naming conventions. Just out of curiosity- if you dropped the pan today, what would you fill yours up with?

I used the Mobil1 Synthetic ATF suggested by Y2K, which has also been highly recommended by Mark Kovalsky.

thanks Jason. I think I will do that. I have read the threads Kovalsky weighed in on and nobody seems to have an issue with that Mobil1.

here’s a separate question. The Mishimoto cooler upgrade is like 40% off right now. Should I install that considering:

1. I dont tow often and certainly never heavy.
2. I live in a state that can see winter temps get to single digits.

basically- is it possible i run the transmission TOO cold??

I would do a complete fluid change first using Mark’s method.

is this the drop the pan, change filter, pull the return line, and run the old fluid into a bucket?

Here is the post by Mark Kovalsky, where the procedure explained in detail:

https://www.ford-trucks.com/articles...-transmission/

I did it just like that and also installed 6.0 ATF cooler & external ATF oil filter, just like described elsewhere in this forum.


These are not my photos, but borrowed from posts by others on this forum, I hope it OK to show them here:

https://cimg2.ibsrv.net/gimg/www.for...b207ba233c.jpg

https://cimg2.ibsrv.net/gimg/www.for...07ef78df74.jpg

my Opinion is yes, I bought the 6.0 cooler at full price.
the difference is quite noticeable,

If your trans temps never show signs of being high then it’s probably not needed, but I do like the 6.0 cooler we installed and knowing it will handle basically anything thrown at it.

Maybe a “best plan” is to monitor trans temp for a while and see if you think it warrants adding the bigger cooler? But if they’re on sale right now then…. :-X04

I have heard running too cold is not ideal due to condensation, but don’t know what makes “too cold.” Mine doesn’t get driven regularly during the cold weather (garage queen hiding from salted roads) but I’ve not been concerned with what I see during cold weather.