Transmission flush question

dasapir · Post by **dasapir** » 30 Oct 2006, 17:32

A quick question regarding ATF flushing as described using the trans to radiator hose method. When flushing with ATF dexron III does it need to be the same high quality during the flushing as one finally adds to the end fill?

In other words, I plan on finishing with Mobil 1 synthetic so should I flush and spill 8 qts of Mobil 1 (I groan at such a waste) or can I use a less expensive (ie. lower quality/lower cost Castrol non-synthetic Dexron III) to do the flushing? My presumption is that near the end there will be some residual left in the transmission of the lower quality flushed ATF and therefore one should use the high price spead throughout. Or is almost all flushed out and therefore can one get away with the less expensive flush?

I would be much obliged if anyone could answer this simple querry.
thank you, thank you

Post by **MadeInJapan** » 30 Oct 2006, 19:33

This is being discussed right now on Swedespeed.com. A guy there is saying that his mechanic flushes his transmission with low quality DexIII ATF before switching to the Volvo (expensive stuff) or Mobil-3309 (both are for later model Volvo's- not yours) to save him money. I guess it doesn't matter if a small amount of DexIII stays in his tranny so, to answer your question, it wouldn't matter. Since our tranny's hold almost 8 quarts I would go with 9 quarts of Mobil-1 ATF and the rest something else to make sure you get almost all of the old stuff out.

Come to think of it, that's really not much of a savings...say you use 12 quarts total for the flush...3 is the $2.50 stuff....so you spend $7.50 total (plus tax), and 9 quarts of Mobil-1 which is around $6.00 around where I am...$54.00. Add these together and you've spent $61.50 plus tax, versus 12 quarts of Mobil-1 for a total cost of $72.00. You saved just over $10.00. I guess I will continue flushing with Mobil-1 and not using cheap stuff in my case...it's about a $10 savings every 30K miles or so and I know that there's actually more synthetic in my tranny (although the total amount may be very very small compared to the way you mention).

Speaking about flushing and trying to get out as much of the old as possible, this is what I would do. Drain the tranny pan by undoing the drain plug (make sure you get a new aluminum crush washer...I understand the same one we use for an oil change works fine). Measure the amount that came out. Fill the pan up with the same amount through the filler tube (dip stick tube). Most of your tranny fluid stays in the torque converter, radiator and the lines, so only about 3.5 quarts should come out. NOW, start your flush with Mobil-1. Run it until clear (well red, and not brown). You'll probably still use 8 or 9, or maybe even 10 quarts of Mobil-1 ATF but more of the old stuff is sure out of there. Plus, since the drain plug is magnetic, you'll have peace of mind by examining it for metal particals and also getting rid of the sludge on it.

dasapir · Post by **dasapir** » 30 Oct 2006, 20:28

Again, as usual, thank you MIJ!
Just got back in from working on my wife's windstar, sorry for the tardiness in replying.
From what I gathered from previous write-ups after flushing there is only a top-up of about 3.5 qts. Perhaps my arithmatic was wrong, but as was discussed I was planing on flushing with 8 and topping-up with 3-4 Mobile 1.
I bought castro at 3/qt x 8 = $24 then the top-up with 6.25/qt x 4 =$25.
total cost with mobile 1 = $75. overall saving $26. $75/30,000 =$ 00.0025/mile. So right you are. complete flush with Mobile 1.
So to double check, after draining the trans and re-filling, I will run the trans
from the tran-to-radiator hose ( purchased 1/2" id clear tubing) to a pan until I see bubbles (this should be about 2 qts. refill and continue onward in this fashion until clear (about 8-10 qts). then top up according to usuall check transmission protocol.
thank again for your undivided attention. will check sweedspeed.

Post by **MadeInJapan** » 30 Oct 2006, 20:59

dasapir, Remember that there are 8 quarts total in the system. After you do a total flush, there will be very little topping off (not 3-4 quarts as you first said), as you've replaced ALL that came out. Of course you want to check the level and top off as necessary...but you'll use very little then. You might even have too much and have to drain a bit out...but you should be very very close to what was in there to begin with (8 quarts).

Let's make sure you have the actual BASIC flush down: Empty out 2 quarts through the clear tube and then stop the engine and replace the 2 quarts through the dip stick tube, and repeating again and again (6 times) until the fluid is clear...about 12 quarts if you ONLY do the basic flush.

Now, what I suggested...a MODIFIED Flush: Drain the tranny by the drain plug (about 3-4 quarts will come out). Use an aluminum crush washer and tighten back the drain plug at 28ft lbs). Fill with cheaper DexIII ATF through the dip stick hole, then do the BASIC flush (above), but don't use 12 quarts, but instead 8 quarts of Mobil-1 ATF (but buy 9 for topping off and to have some on hand).

Remember that the total system has 8 quarts of ATF in it to begin with- 3.5 or a bit more in the tranny (pan), 4 or so in the torque converter and radiator (tranny oil cooler) and some in the lines. So, what you'll actually see (if my theory is correct, and it should be) when you start a flush with the modified method is dirty fluid coming from the radiator and torque converter first (first 4 quarts or 2 engine on- engine off cycles) and then suddenly your AFT that is being drained out will clear up (from the cheap DexIII you added at the beginning). Don't let that fool you...It's coming through to flush out the darker dirty fluid. keep flushing twice more (for a total of at least 4 cycles). Now you've used 8 quarts of Mobil-1 along with the first 3.5-4 quarts of cheaper DexIII you added at the beginning. Use the extra quart of Mobil-1 synth to top off and also have around if you ever needed to top off again.

dasapir · Post by **dasapir** » 30 Oct 2006, 21:27

MIJ, got it. The confusion lay in the difference between the straight flush and your modified technique. By the by, for the difference in price between the cheap and good I will just dole out for the Mobile 1. and not think twice about it.
take care.

Post by **MadeInJapan** » 30 Oct 2006, 21:33

I have never done the drain and fill and then flush technique before. All I've done is the straight flush, but the more I've read about this I've decided that the next flush I do will be a drain and fill and flush...all with Mobil-1 on my S70 (Mobil-3309 with the V70), as this way I can check the condition of the internals better...by looking at the drain plug, and it will give me a chance to clean that thing off...never done it so don't know what's on it....Plus you actually do get more of the old fluid out rather than just diluting it with the new to begin with. I think that using the same amount of fluid I'll get a much cleaner flush. In fact, this is a money saver as I think I can get away with using less fluid if I wanted to this way.

Good luck and let us know how it went.

dasapir · Post by **dasapir** » 31 Oct 2006, 19:34

Okay, MIJ, the flush went well. Not a problem with your modified methed.

a few things for posterity:

1). It took 9 and coulda used 10 quarts to flush it clean. perhaps more is necessary because of the initial draining or this having been the 1st time I changed out the ATF, but at 8 quarts it still looked pretty burnt (Used 5' 1/2" id clear tubing hooked to the tranny line. good tight connection) . At 9 good. 10 quarts would have been ouu-la-la! FYI Initially it drained
3 1/4 qts very burnt transmission fluid from when I drainded the pan using the drain plug.

So in the end short a quart and will need to got out to get the last to top-up.

The drain plug looked rather good, especially since I have 74,000 m. on the car without ever doing the atf. Not much in the way of metal particles.

2). The 24 mm/ 15/16 inch wrench needs to be preferably a box or open end. Learned my 1/2" drive 15/16" ratchet won't fit between the gas lines which run right next to the trans drain plug. so for others- a box or open-end.

3. No-one , no, one in town carries crush drain plugs to fit. Next time I make a large order from FCP groton need to order some.

4. Snap-ring pliers make it almost a dream to take off the top trans-to-radiator line. do not leave home with out them.

So next time you do yours go for it. By the way I put the car up on Drive-up to get under and I am quite small and still it was tight.

regards.

Post by **MadeInJapan** » 31 Oct 2006, 20:19

Hey, glad it worked. Good job! Great info on everything. Don't recall the fuel line being in the way on mine but I'll check before doing my next flush!
Okay, 10 quarts it is! I know you're feeling good that this is behind you. How does she drive now?

dasapir · Post by **dasapir** » 31 Oct 2006, 21:04

Sorry, must wait until tomorrow. I am shy 2 quarts Mobil 1 and will need to pick up the ATF before I test her.

By-the-by, received the silicone vacuum hoses today from stylinmotors. Picked up a K&N filter today and I am just waiting for the order to come in from FCP Groton.

As I mentioned earlier a week at the spa, perhaps will polish the car afterward. Next spring probably the timing belt since over 70,000.

Any other suggestions. I am ready to listen and learn.

dasapir · Post by **dasapir** » 01 Nov 2006, 19:38

Well , I wasn't short the 2 quarts. I had purchased them, but had not placed them with the other mobil 1 quarts for some unexplicable reason. Anyway, topped the transmission off late last night and test drove the car.

How smooth it is! No hesitation in shifting. I was completely unaware what a difference a flush would make. Cannot say whether or not it is just clean good ATF or also the change to a complete synthetic such as Mobile 1.

Again, MIJ, I cannot thank you enough for all your help and advice.