Tranny drain and fill - percent new fluid

[bkgee]

Folks, after contemplating all the various methods for transmission maintenance, I decided that I would go the simplest route: drain and fill, drive, drain and fill, etc. I calculated the percent new fluid with each drain and fill, so I thought I would share that here.

The calculation for fluid mixing is simple: Co*Vo+Cn*Vn=Cm*Vm, where C is concentration, V is volume, o is old, n is new, and m is mixed.

The first drain is about 4 quarts (Vn), leaving about 8 quarts (Vo) in the tranny. Solving for Cm (the percent new fluid), the first drain/fill gives 33.3% new fluid. The second drain/fill gives 55.5% new fluid. I drove around the block, shifting between gears, to mix the fluid between each drain/fill.

Third=70.3%
Fourth=80.2%
Fifth=86.8%
Sixth=91.2%
Seventh=94.1%
Eighth=96%

I only did three drain/fills and the fluid looks pretty good.

This method costs more than the fluid replacement through the tranny cooling lines, if you want to get the high% new fluid. But this method is certainly easier than dropping the pan and/or screwing with the cooler lines - I think its about the easiest fluid to change on this truck period. I decided to go this route hoping that I would not need to drop the pan until my next major service interval at 180K miles (my truck only has 120k miles now). I will probably continue to to a drain/fill at each engine oil change (every 10k) until then, keeping the fluid between 70 and 80% new - this would be similar to having had the full service "recently" all the time.

Its not that I don;t have better things to do, I just like numbers.

 

[spressomon]

This is the way I've been doing mine too (Amsoil). 4Q every 10K at oil change time. And I believe the least risk to effing up the tranny especially compared to the full detergent power flush so many tranny shops like to sell

 

[Travis351]

Wow...thanks for sharing. I was wondering what everyone else was doing for tranny service. I have been doing drain/fills at 30k intervals.

 

[1loudLX]

Joe@Slee did mine with the machine using the tranny lines extremely quickly, and easy since the LX's grille comes up when you open the hood. I went with that method since it was the best way to get all of my oil fluid out at once. Now if only I got around to doing drain and fills regularly.


btw, bkgee, you must have been able to figure out the water jug problem in die hard really quickly huh?

 

[bkgee]

btw, bkgee, you must have been able to figure out the water jug problem in die hard really quickly huh?

I wish i was quick, but i am very slow with computations. like my wrenching, it usually takes me 3x

 

[spressomon]

FYI: While your at it might and have the AT fluid handy might as well take a good look at the power steering reservoir/fluid. It sure seems to take a beating on my rig. I can't but go about 1-year without it turning dark and contaminated looking.

Turkey baster; empty/fill/power on and turn the steering wheel stop to stop and repeat until you've got clean fluid.

 

[bkgee]

I might try the turkey baster next time. This time we just routed the reservoir-in hose to a jar and filled the reservoir as we went. There was terrible pump noise and very aerated fluid, I dont think we did any damage but the baster seems more civilized!

 

[arbetrader]

Sorry guys, I'm sure it's already posted somewhere, but what's the best (most ideal) brand (or type) of ATF to use? Please post both for your AT and Power steering. (I'm assuming I can just use the same stuff right?)

 

[bkgee]

I used Mobil1 ATF, an many others here do too. Expensive, but good for longer drain intervals. Others use Amsoil and Redline, and I figure plenty of people use conventional dino too with good results. The synthetics virtually eliminate regular internal wear.

 

[arbetrader]

I used Mobil1 ATF, an many others here do too. Expensive, but good for longer drain intervals. Others use Amsoil and Redline, and I figure plenty of people use conventional dino too with good results. The synthetics virtually eliminate regular internal wear.

ok, but I doubt the previous owner used synthetic oil in the trans or ps fluid and there's already nearly 150k miles on my truck. Can this be detrimental to my vehicle given the k's or does this general rule of thumb only apply to engine oil?

 

[bkgee]

i dont know if that rule of thumb applies to other than just engines, but several folks here have reported no onset of engine leaking after switching to synthetics, at very high miles. i just switched, but its too early for me to tell, only like 30 miles ago.

 

[NMuzj100]

That "rule of thumb" regarding synthetics is at least 20 years out of date if it was ever true.

I have used the baster method but last time I just pulled the lower hose, drained the reservoir into a container, reattached hose and filled. Repeat as needed. Much easier, faster and cleaner.

I use Amsoil ATF in both. If I had a WS transmission I would use Amsoil ATL in it and the Amsoil ATF in the powersteering.

 

[mtnracer]

Folks, after contemplating all the various methods for transmission maintenance, I decided that I would go the simplest route: drain and fill, drive, drain and fill, etc. I calculated the percent new fluid with each drain and fill, so I thought I would share that here.

How do you drain it without dropping the pan or using the fluid lines?

 

[bkgee]

drain bolt on my 2001

 

[mtnracer]

drain bolt on my 2001

Drain bolt on the pan?

 

[Jim_Chow]

Pulling the ATF cooler lines is the easiest way to change all the fluid. I had my dealer do this, put in 12 qts of new T-IV. Repeat every 30K miles.

 

[bkgee]

Drain bolt on the pan?

Yep, its tucked right up near a cross member, and drains easily with no mess. This option was discontinued in 2003 5-speed I think.

I was going to do the job Jim_Chow is referring to, but this method seemed just a bit simpler than messing with cooler lines and running the engine. I added another drain a week later since I had some fluid left - the fourth drain looked very much like new fluid.

I will probably follow spressomon and drain the pan (4 qts) every oil change, until my next major service (180k), then drop the pan to clean it out.

 

[1loudLX]

2004s didnt come with the dipstick, but 03s did. I think they have the drain plug.

 

[mtnracer]

Just checked under the truck and it looks like I have a drain plug on the pan (right in front of the center diff).

How much will drain out when I open that plug? I just want to make sure I add the proper amount after I drain it.

 

[bkgee]

My drains were about 3.5 qts. Have four qts ready for each drain. Regardless, you fill to the appropriate level on your dipstick - measure this level only at operating temperature and while the engine is running - i gather that the 'cold' markings are not reliable.

If you do not have a dipstick, then your procedure will be different and I would verify all of that before you get started! good luck,