mixing ATF

Joined
May 6, 2009
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Northern IL
I wanted to change out my trans fluid to royal purple and didnt want to get a flush done but instead since my truck has a drain plug on the pan i was gonna pull it and drain the five qts and refill with RP then drive for a bit and reapeat two more times getting most of the fluid changed would this be ok to do since it will mix the fluids a bit
 
Joined
Jul 22, 2007
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674
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Nebraska
I think you would be OK if you get as much of the old stuff out. It depends on how much comes out in your plug and how much is held in the converter. What I did on my wifes Honda was drain it (started it up and another 1/2qt came out. Then drove it for 15 minutes, drain and refilled and reapeated that step again. Granted I didnt mix brands I used the Honda OEM fluid, but IMO if you get as much of the old stuff out you should be OK.
 
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Joined
Dec 2, 2002
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Washington St.
There is no way to do a 100% fluid change nor to avoid any mixing without disassembling the transmission and wiping the internals dry. 4x4, consider doing a flush yourself through the cooler hoses. Drain and refill the pan first, then flush through the hoses. With care, you won't make a mess and you'll get a good job. Heavy, the Honda transmission is one of a few that drains a much larger proportion of the fluid than most. Three drains and refill of a Honda are nearly as complete as a flush.
 
Joined
Feb 1, 2003
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RI
Its perfectly acceptable. You don't need to do a flush if you don't want to. Usually a flush will use less ATF then multiple drain/refills. Drain/refills tend to be easier. Time or money is your choice.
 
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Mar 21, 2004
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Upstate NY
Why not do a cooler line flush yourself. Easier than you think if you have rubber lines going to the cooler. Multiple drain and refills are not cost effective with expensive ATF.
 

4x4chevydude

Thread starter
Joined
May 6, 2009
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701
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Northern IL
cause they arent rubber and ive had a terrible experience with trans lines in the past replacing trannies that tend to snap if they are a little rusted which mine are
 
Joined
Jun 15, 2004
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South Carolina
If it's a GM, good luck getting that drain plug out. It's usually near impossible. Makes me wonder why they bothered to put a drain plug in those pans. The cooler line flush just might just be easier than you think. Really.
 
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