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Transmission Fluid Changeout Calculator

5K views 33 replies 7 participants last post by  06DGC 
#1 ·
I found this cool spreadsheet that a guy from silveradosierra created. A person could do the math, of course, but this is convenient.

ATF Changeout Calculator

Based on a 9 quart factory fill and top up, 2 drain and fills (replacing 5.5 quarts each time) would leave about 2 quarts of old fluid in the system.

I sucked out and topped up with a little bit more than 4quarts before I did my pan drop and filter replacement and pan with drain plug install. Then I added about 6 more quarts. I'm going to do one more drain and fill and call it good.
 
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#2 ·
If one gets 50% out with each drain, then the calculation goes like this
50%
25%
12.5%
6.25% old fluid left in system after 4 drains/refills.

6.25% of a 9 quart system = 0.56 quarts of old fluid left. I use a similar calculation for coolant change.
 
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#5 ·
If one gets 50% out with each drain, then the calculation goes like this
50%
25%
12.5%
6.25% old fluid left in system after 4 drains/refills.

6.25% of a 9 quart system = 0.56 quarts of old fluid left. I use a similar calculation for coolant change.
Haha. I was thinking of you, Church, when I said, "a person could do the math".
 
#3 ·
R = ( ( X ÷ C ) ^ n ) × 100
Where R is the percent remaining of old oil
C is the total Capacity
X is the amount exchanged
n is the amount of times the fluid is exchanged.

O = ( ( X ÷ C ) ^ n ) × C
Where O is the remaining quarts of old oil
C is the total Capacity
X is the amount exchanged
n is the amount of times the fluid is exchanged.
 
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#6 ·
Us shade tree mechanics would love a drain plug. It is cheaper to make pan without one, plus it forces you to remove the pan to check for debris, clean the magnet and change the filter.
 
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#9 ·
The junkyard A604 transmission I pulled apart this weekend had nasty, dirty fluid, and saturated magnet on the pan. The clutches look brand new inside.
Based on this single data point, you could trash many fills worth of fluid and still have a good transmission.
 
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#14 ·
That is interesting. (y) Did you have a chance to look inside the valve body?
 
#11 ·
I will offer that the majority of non-forum members have no clue about changing any fluid other than motor oil. If the trans oil change were made easy, any number of shops would 'offer' to change the trans fluid and likely refill with the wrong stuff that destroys the trans months/years later.

A number of backyard mechanics would not read the dipstick (if present) that notes the engine must be running and trans in park and that trans fluid temp is important. Heck, they may even grab the cheapest universal trans fluid on the shelf and not the right stuff.

Then it all comes back to the manufacturer that the trans is unreliable....
 
#22 ·
"I have no idea how that 2 × 4 got wedged between the seat and the gas pedal!"
 
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#23 ·
🤣 🤣🤣
 
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#24 ·
ATF+4 transmission fluids don't wear out and the system is pretty much closed loop. They can get a little dirty, and more so, if something is wrong. The additive package in the fluid can deplete and hence the need for replenishment under severe duty conditions.
The fact that many transmissions have their filter buried inside them, indicates filters don't really need to be changed. The 8 and 9 speed ZF designed transmissions, used in the Jeep Wrangler and Pacifica, have lifetime fluid I believe.
ATF+4 was a great improvement over ATF+3 as far as longevity is concerned.
From: Chrysler automatic transmission fluids: 7176, ATF+3, ATF+4
ATF+3 is a friction-modified, high-quality transmission fluid similar to the current fluid in most respects; but it wears out more quickly and has less desirable cold viscosity (to simplify: is too thick when cold). ATF+3 can be approximated by Dexron plus an additive but this does not save much money and is not as desirable as using the correct fluid to begin with.
The big differences between ATF+3 and ATF+4 is that ATF+4 uses a synthetic (Group III) base oil and a Lubrizol VI improver in the additive package..
Lubrizol developed a new shear-stable viscosity index (VI) improver
Developing ATF+4 was to create a fluid that would match the performance characteristics of the current fluid (Type 7176D), but would retain those characteristics for at least 100,000 miles. The paper specifically notes that the anti-shudder properties of ATF+3 are usually degraded enough by 30,000 miles to cause noticeable shudder.
 
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#26 · (Edited)
ATF+4 transmission fluids don't wear out and the system is pretty much closed loop. They can get a little dirty, and more so, if something is wrong. The additive package in the fluid can deplete and hence the need for replenishment under severe duty conditions.
The fact that many transmissions have their filter buried inside them, indicates filters don't really need to be changed. The 8 and 9 speed ZF designed transmissions, used in the Jeep Wrangler and Pacifica, have lifetime fluid I believe.
ATF+4 was a great improvement over ATF+3 as far as longevity is concerned.
From: Chrysler automatic transmission fluids: 7176, ATF+3, ATF+4

The big differences between ATF+3 and ATF+4 is that ATF+4 uses a synthetic (Group III) base oil and a Lubrizol VI improver in the additive package..
According to this thread at BITOG, ATF can shear.

ATF Degradation

I don't think heat should ever be a problem for ATF in the 62TE - at least in the vans. I tried hard to get the ATF up to 180 - not beating on it or anything - but I was hard-pressed to surpass 150F. I use AppCar DiagFCA. It's definitely the heat of summer around here and maybe it will approach 180 in the summer. My turbo Toyota runs around 170 - 180 after about 1/2 hour on the highway and I have a dedicated cooler. If I'm boosting a lot at low speeds, I've seen it approach 200.

As an aside, I picked up Fusion OBD and the enhanced pids pack. Haven't spent long with it, but it looks like it's going to blow Torque Pro away. After installing, the app scanned the computer and appeared to find over 5000 pids. In short order I had ATF temp displaying. I'm going to cross reference with AppCar to see how close they are. AppCar will be the benchmark as I trust it - not 100% sure why - but I do. Haha.
 
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