mixing ATF types...

[pbm]

I have come to believe that mixing brands of motor oil only diminishes the positives of each brand. Is this true for ATF also?
For instance if I use Castrol Import ATF in my Accord how will it mix with the Z-1 thats already in the tranny? I have about 3 quarts of old ATF+3 and I'm thinking of using it as the first of 3 or 4 D&R's in my Honda Accord and finishing off with 2 or 3 fills of Castrol Import. My thinking is that the ATF+3 will act as a flush. What percentage of +3 would still be in the tranny?

 

[oilboy123]

I would say in general it's not good for any fluid. I'm not touching your percentage question with a ten foot pole.....

 

[pbm]

I remember reading that after 3 or 4 D&R's there is virtually none of the original fluid left. The thread mentioned how much original fluid was left (percentage wise) after each D&R. I can't find it now.


What about using the +3 as a flush...any thoughts?

 

[mechtech2]

Motor oils are designed to be OK when mixed, as the SL , SM, or whatever designation allows this.

ATFs are also specifically designated. So different brands are OK. but not different types. We have to be careful here. Different friction characteristics, viscosities, etc. are concerns. Trannys can be sensitive to different fluids in operation and long life.
Old auto trannys are different. You could get away with almost anything. No lock up converters, solenoids, electronics.
We have to strongly consider what the factory recommendation is, now.

 

[eljefino]

Look up your total vs drain capacity and make it a ratio. IE if you held 7 qts and drained 3 you'd have 4/7 old fluid remaining or .5714. Do the .57 to whatever power is the number of changes you do... 3 changes for example would be 18.6% old fluid.

 

[JakeR22]

I would, and have mixed motor oils, and trans fluids, with no worries. As long as they're the proper fluid, I don't care about brand.

 

[pbm]

Originally Posted By: eljefino
Look up your total vs drain capacity and make it a ratio. IE if you held 7 qts and drained 3 you'd have 4/7 old fluid remaining or .5714. Do the .57 to whatever power is the number of changes you do... 3 changes for example would be 18.6% old fluid.


El: I understand the first half of your post but could you explain the ".57 to whatever power" part.
Math wasn't my best subject.

 

[Oldmoparguy1]

Man oh man, why do we have to over think everything???

ATF +3 is discontinued, ATF +4 is the direct replacement. +3 is semi-syn, +4 is full syn.

Just use up the +3, then go with the +4.

OBTW: In an emergency you can use DEX II or III. My 2000GC owners manual says so.

 

[mechtech2]

omg - Things are different now. We really should use the type of ATF required.

 

[unDummy]

No, then you would be stuck with OE fluid everywhere.
I can only imagine the day when we are forced to use OE windshield washer fluid.
Dealer service department in 2020: "Sorry, but the air that you put in your tires voided your tire warranty".

If you require Z1, then ATF+3 is your risk to take. You could always give it away.

Stick with the Import or Highmileage Castrol if you plan on doing drain/refills in the future.