mkgarrison5

hey guys i have been debating switching over from my current Maxlife Dex\Merc atf fluid to M1 tranny fluid.. the maxlife all i have done is drain and fills since i bought the truck with 52k miles (97k miles now) every 15k miles or so. 4 qts at a time. i am curious couldnt i just do drain and fills with M1? do you think the two would be ok to mix? i dont have the $$ to buy 16qts of M1 and to pay for someone to flush and refill with M1 so what i was going to do was to stick with my regular schedule (15k miles 4 qt drain and fill) except using maxlife just use M1.. what do you guys think?? thanks in advance

ARB1977

The flush part is really easy. When i did the change over to Redline D4 i disconnected the return line after the coolers, started her up and pumped out 4 qrts, shut her down, refill the pan with 4 qrts. Repeated process till she was bright red. Currently ive got Redline D4 and Amsoil Universal atf. I drain the atf every other year.

mt_goat

Wow 4 quarts at a time? I'd be worried about running it dry. I'd maybe do 2 quarts at a time.

mkgarrison5

yeah i wont go over 1-2 quarts bc it will be running dry over that. you maybe doing more harm than good. where is the return line located on a auto v6 4x4?

mt_goat

The return line is the one nearest the back of the tranny, closest to this label:

The line out is nearer the front.

86tuning

If you're worried about the tranny running dry, you can always fill it while you're pumping it out thru the return pipe.

Seriously though, as long as it's in PARK you'll be fine. Shut it off as soon as the flow slows down, fill, etc.

mkgarrison5

but isnt the tranny still turning even in park?? iwas told NOT to pump out more than 1-2 qts period!..

mkgarrison5

i am assuming that its the only line near that label and i couldnt miss it? lol sorry never really paid that close attention to the tranny other than looking for leaks. thanks goat

mt_goat

I probably should say you don't want to disconnect the line there but you can follow that hard line to the front of the truck and after it goes to a rubber line dissconnect the rubber line there.

mkgarrison5

10-4, ill get a closer look sometime soon. anyone just happen to have pics? if so great if not, not a big deal, ill find it

mkgarrison5

i am curious, couldnt i just do drain and fills with M1? i know its not the same as dumping the old fluid but over time it does. it would be M1 mixed with my current Maxlife atf. any issues anyone know about mixing them?? thanks guys. thats just out of curiosity

ARB1977

Theres plenty of fluid in there...no worries here.

ARB1977

Did it at 30K and with 75K now no problems.

mkgarrison5

good luck to ya on that one. ill just stick with 2 when i ever get around to doing it. no harm. hopefully (fingers crossed)... when you guys switched to
M1 atf what difference did you guys notice? at 97k miles i have no complaints other than the noticable shift from 1-2 when its cold, after it warms up its fine. i am assuming the maxlife is a little thick, i know the motor oil is fairly robust.

GSGALLANT

There is not plenty of fluid in there.

The tranny pump suction is through the filter. The filter's opening is near the bottom of the tranny pan when the pan is installed, but I suspect there is probably roughly 1/4" to 1/2" of clearance between the filter opening and the bottom of the tranny pan (I haven't measured, but let's say 1/4" for arguments sake).

Going by memory, the size of the tranny pan is something like 16" to 18" long by 7" to 8" wide or so? Meaning that every 1" of height in the pan holds approx 2 to 2.5 quarts of fluid. Assuming best case scenario that the filter opening is only 1/4" away from the bottom of the pan, that leaves approximately 0.5 to 0.6 quarts of un-useful fluid in the bottom of the pan (i.e. the tranny pump will run dry with 0.5 to 0.6 quarts left in the pan).

Now, the A340F tranny pan holds approximately 4 quarts when you drain it via the plug, and maybe another 0.25 quarts (max) held up in the low points in the pan that don't drain via the plug. So by my calculations (rough as they may be going from memory), you are getting dangerously close to starving your tranny pump of fluid by doing 4 quarts at a time (and that's assuming your truck is level on the jackstands when you're doing this). That's why I (and most others) only do 1 or 2 quarts at a time when we flush our trannies. The extra bit of time it takes to do 1 or 2 quarts at a time is worth it to guarantee I won't damage one of the most expensive components on my vehicles.

Look at the bottom of the radiator on the side that faces the rear of the vehicle. There will be one small line coming out of the passenger side and one small line coming out of the driver side. Those are your tranny cooler lines. I can't remember which one is which, but follow them back to the tranny... the return line to the tranny goes into the tranny further back than the other one. So when you identify the return line, go back to the radiator, disconnect the return line where it changes from hard line to rubber line. If you have the right line, fluid should come out of the end that's still connected to the radiator when the vehicle is started.

Mixing the two fluids is probably OK (most ATF brands are compatible with each other... as long as you're not mixing different types of ATF), however, for the little bit of extra work involved with flushing it, I would recommend the flush so that you know that you are left with a tranny full of brand new M1 fluid.

mkgarrison5

good point gallant... .. side question, how long does it take for new aft fluid to mix good with the old given you did a drain and fill? is the pressure and flow of the atf fluid pretty strong? or does it take some time for it to mix?

GSGALLANT

The flow through the cooling lines is high enough to fill a 2 quart container in probably... 15 to 20 seconds or so. It's been almost a year since I did mine, so the memory is a little fuzzy, but I think I'm close. The pressure is quite low... maybe 5-10 psi or so.

Bottom line is the fluid will be fully mixed quite soon (a minute maybe?) after you start the vehicle after doing a drain and refill only.

mkgarrison5

oh ok.. still trying to make my mind up whether to pull the cooler line and do it that way or just do drain and fills with M1... though it would be mixed with maxlife

k_southman

What is the capacity of the entire ATF system if one was to do a complete flush? Don't want to buy too much, AMSOIL SYNTHETIC ATF is expensive!!

GSGALLANT

13 to 15 quarts, depending on whether you're doing your 1991 or your 2000.

The A340H on the 1991 (if your 1991 is an auto) takes approx 13 quarts to flush, then the drain and fill of the transfer chain case (which is also filled with ATF) takes a little over a quart. The A340F on your 2000 (if your 2000 is an auto... and I assume it's a 4x4 since you have a rear locker), takes roughly 14 to 15 quarts to do the flush.