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change trans fluid after 100k

3K views 16 replies 6 participants last post by  MoyockPowerstroke 
#1 · (Edited)
I have heard that if the trans fluid has not been changed with in 100k then dont bother cuz if you do, then the new fluid will destroy the trans.

I have been askin arround and but gettin notin on how giving a trans the fluid it needs can hurt it after on the first change after 100k.

I have heard this from many people but never heard why.

Thanks
 
#2 ·
I'm not buying that...all lubes and oils have viscosity properties that deminsh over time, etc... I would definately change it and also the external filter. Using only Mecron SP or LV of course.
 
#5 ·
I've read horror stories of the same tune and have been hesitant to change my fluid, Stupid maybe... I dunno. I'll wait to hear other responses...

How many qts does my truck take anyways to drain and change filters? (2003)
If just dropping the pan plug, then 7 qts will do it...I'd use another to add some to the external filter canister before re-assembly and you will also have more if you need to top off after checking your fill levels (while warmed up and running at idle). You will most likely want to do this again after about 1000 miles of driving, then again after another 1000 miles...then you should be good for another 30k miles, then just replace 7 qts each 30K (along with a new external filter).
 
#7 ·
P.S. then tranny temps have to reach 170*F or more before the fluid in the TC actually cycles completely thru the system, so the "Quick lube joint" hot flush isn't worth the mony IMO...I'd go with just cycling of drain and fill method as mentioned earlier.
 
#8 ·
Personally if the pan isn't leaking...then I'd leave it alone. Of course if you oull it, then more fluid is needed. Just replace the external filter, unless you plan on upgrading the pan to the '08 MY with the better internal filter, otherwise the earlier MY internal filters are long life filter (screens), and most likely are fine....it becomes a problem when you start messing with the pan bolts and cannot get a good seal on the reusable pan gasket.
 
#9 ·
Dropping the pan is no big deal. There are bushings in the gasket that won't let you over-torque it when you put it back on. With 100k on original fluid, I'd definitely change the pan filter too.

Whoever said new fluid would hurt the transmission is nuts. What will hurt it is running with worn out fluid that has lost all its original properties.
 
#10 ·
i only have a 7.3, and i know this is a 6oh thread...

but i heard the same thing. my 99 now has 132k on it. i went ahead and changed the trans fluid with a full flush a few thousand miles ago since i dont know when the last one was done. i bought the truck at 119k and hadnt had an issue so far. the old fluid almost smelled burnt. so thats why i went ahead and flushed it. next time will just be a pan drop. i do see my trans get up to 170ish on warm days here with city driving. i guess time will tell. im just tryin to avoid a rebuild right now lol.
 
#12 ·
well i got my trans flushed at 145k at the ford garage. the only problem i had was a vent tube that is on top the trans it was pluged and i guess from the pressure cracked the tube and was leaking trans fluid. that is what i was told by ford its fixed with no leaks.
 
#14 ·
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