Hi everyone. About a month and a half ago, I had my transmission fluid drained and filled. After it was done, I checked the fluid myself and it was pink. Checked it again recently and now it is brown. I want to do another drain & fill to get the fluid pink again but is it too soon? My mechanic advised me to have a drain and fill done every other oil change.

 

Not too soon, you are good to move forward...technically you could just take it around the block a couple times and do it again if you want. There is an official Toyota grid that says if you do #1, you leave 54% old in the tranny. #2, 31% old. #3, which is where most recommendations say is enough, 17% old.

Since you checked the fluid I take it you have a dipstick.....I don't, but the tech put mine aside so I could see. When #2 was done, what came out was black, but not burnt. He did #2 and #3 on the same visit, so he didn't charge me labor, just for the WS fluid, extra 2, 5 total. The idea is you need 2.5, so if you do a single drain and fill, there would have been .5 qt left, so charging for 3 is accurate.

 

The AT holds about 12 quarts of fluid. A drain and fill only drains and replaces 2.5-3 quarts of that total at a time. So if one drain and fill is performed, the fluid check afterwards should show lighter color AT fluid, but not same color as brand new undiluted fluid because the old remaining AT fluid has mixed with the new fluid. As posted above repeated AT drain and fills will produce lighter and lighter color AT fluid checks as more of the old fluid is replaced with new fluid. I did 3 sequential drain and fills on my car (with a few miles of driving in between each D&F) at about 70k miles and the fluid ended up looking pretty clear and not dark at all.

I will likely do 3 more AT D&Fs at 140k miles. My 06 does not have a dipstick so the D&F process is a harder and more labor intensive to perform correctly than for 01-03 LS430s which have a dipstick.

 

I know that the "dry fill" number is 11.5 qts., but can someone explain why the % on the grid are based on old divided by 5.6 qts. (3.1 + 2.5)? Meaning, if you introduce 2.5 qts. new, on the first drain/fill, why isn't it 2.5 divided by 11.5 = 21.7% new, or 78.3% old? I am willing to accept the chart stating 55%, 31%, 17%, of old left after each drain/fill, but curious about the math.

Here is a nice pdf, page 21 discusses the drain/fill. This is the tranny without the dipstick btw.

A761E
http://shop.ukrtrans.biz/wp-content/...logs/A761E.pdf

 

I worked the numbers for each Drain and Refill, and the results are not nearly as optimistic.

Assume we start with 11.5 quarts in the transmission, and each D&R we exchange 2.5 quarts. Please note that for each D&R, we will be draining out ATF with progressively lower concentration of old ATF. In other words, the first D&R we pull out 2.5 qts of pure old ATF; the second D&R we pull out 2.5 qts of ATF that contains only 78.26% old ATF, and the third D&R we pull out 2.5 qts of ATF that contains only 61.22% old ATF, and so on... As we proceed forward, our ability to extract old ATF will diminish further. Shown below are the calculations:

Drain and Refill #1: Start with 100% old ATF
Old ATF = 11.5 – 2.5 = 9.0 Qts
New ATF = 2.5 Qts
Concentration of Old ATF = 9.0 ÷ 11.5 = 78.26%

Drain and Refill #2: Start with 78.26% old ATF
Old ATF = 0.7826 x ( 11.5 – 2.5) = 7.04 Qts
New ATF = 2.5 Qts
Concentration of Old ATF = 7.04 ÷ 11.5 = 61.22%

Drain and Refill #3: Start with 61.22% old ATF
Old ATF = 0.6122 x ( 11.5 – 2.5) = 5.51 Qts
New ATF = 2.5 Qts
Concentration of Old ATF = 5.51 ÷ 11.5 = 47.91%

Drain and Refill #4: Start with 47.91% old ATF
Old ATF = 0.4791 x ( 11.5 – 2.5) = 4.31 Qts
New ATF = 2.5 Qts
Concentration of Old ATF = 4.31 ÷ 11.5 = 37.48%

Drain and Refill #5: Start with 37.48% old ATF
Old ATF = 0.3748 x ( 11.5 – 2.5) = 3.37 Qts
New ATF = 2.5 Qts
Concentration of Old ATF = 3.37 ÷ 11.5 = 29.30%

 

I follow you 100%. Is the Toyota grid for the wrong car, or what gives, I wonder...is there even a car that would be only 5.6 qts? I grabbed that pic from a former post here....

edit

the 5.6 qt matches the capacity of the torque converter. Again, then, I wonder what the Toyota grid is designed for, and what the % represent? Interestingly, entire transmission assembly says 7.6 qts, implying 4 will never come out?

https://www.clublexus.com/forums/ls-...ml#post5426185

 

And just my .02 cents. Doesn't it say you don't have to change the fluid "UNLESS" you've met one of the special conditions;
For 5,000 mile intervals
Driving on unpaved or dusty roads.
-Towing a trailer or using a camper or car-top
carrier.
-Repeated trips of less than five miles in
temperatures below freezing.
And for 7,500 mile intervals
Use 7,500-mile intervals if you primarily operate your
vehicle under conditions other than those listed above.
and the special conditions are also:
Driving on rough, muddy or snow-melted roads
Driving on salt-covered roads
Driving on unpaved or dusty roads
Extensive idling or low-speed driving for long
distances
Towing a trailer or using a camper or car-top
carrier

I certainly fit the 5,000 mile intervals easily. Not saying I wouldn't and mine was changed but now I wonder is it worth it if the numbers above bear that out? After five drain and fill your still left almost 30% old.

 

From the 2001-2003 repair manual, a drain and fill is 1.8L (1.9 US quarts, 1.6 imperial quarts). However, if you are sure your transmission hasn't lost any fluid, just measure what comes out of the drain plug, and pour that same amount from a fresh bottle back in. If you drain over a long enough time, you should be able to get 2.0L out, and since new fluid comes in 1L bottles, just add 2 bottles. Also note that overfilling a transmission is worse than underfilling. And if you have a dipstick, use T-IV fluid (not WS fluid!).

I also agree that if you qualify for the severe duty cycle as Hagar specified above, you may want to change the ATF at every oil change or 2 (assuming you follow the recommended 8000km oil change interval).