Subject vehicle is a '92 Aerostar with the 3.0 V6 and 120,000 miles. ATF Change history is as follows:

43150 miles: conventional and filter change
68500 miles: Mobil 1 and filter change
86150 miles: Mobil 1 and filter change
102,874 miles: Redline and filter change (install pan plug)
103,500 miles: Redline (no filter)to increase the proportion of Redline

Figuring how much is changed out with a pan drop and for the last change, by he new drain plug, I came up with that currently the ATF is comprised of

60% Redline
25% Mobil 1
15% Dino

It's been about 17,000 miles since the last time I freshened up the ATF. It looks like this:



The van shifts fine, a little on the firm side which I like. Goes into reverse pretty hard though. What do you think. Just change the fluid (filter probably fine after only 18000 miles), or are there bigger issues?

Tranny shop said if fluid is brown not to change it. Said that is the worst thing to do. I think that advice is BS.

 

I would say your fluid is starting to fail and should be replaced. How are you changing the fluid. If done properly, at each change 98%+ should be changed out. The A4LD likes new fluid. If you just drop the pan you will leave a lot of old fluid in your transmission. What you need to do is called a gentle flush and should not be confused with the flush machines used at your transmission shop. This is a simple procedure you can do at home without any special tools. I think the drain plug is not a bad idea, but it doesn't eliminate the need drop the pan.

https://www.ford-trucks.com/forums/5...y-at-home.html

If you use the above outlined procedure, it is possible to change out almost all of the old fluid. I have had this procedure performed on both of my families Aeros, and many other here can attest that the method does extend the life of the transmission and has almost no risk of harmful effects (certainly outweighs the risk of transmission damage by not doing so.)

 

Does that trans have a drain plug in the convertor and have you drained the convertor when you changed the fluid?

 

I don't believe there is a converter drain plug in the A4LD.

The run engine flush seems good, but which way does the fluid flow? I am a little spooked about trying this method.

Someone in another thread said they did it with the engine off and just pumped low pressure air, like from a bicycle pump, into the line and got most of the fluid out. I'd like to try that.

Alternatively, what if I drain the pan, then run it for 30 seconds, drain the pan again, run it for another 30 seconds, and drain the pan a third time? I doubt it would hurt the tranny to run low to empty if only for 30 seconds and not under load. After all, there will be fluid coating all the parts. Or could loosen the line at cooler and run engine to empty then refill through dipstick tube, no?

 

I never could see any possible advantage to having dirty, failed fluid in anything mechanical. Change your fluid and the filter. The filter is probably more important than the oil. There are some strange theories out there.

BMW actually says that you should drain the fluid into a clean pan and reuse it. How could anyone pour dirty drained fluid back into a transmission?

Even in a worn, mature transmission, clean oil simply must be better.

Maybe "Mythbusters" should investigate this one.

Ken

 

I think it comes from people whose tranny fluid is really bad, changing it, then the tranny fails. They attribute the failure to the ATF change because it is so close in time, but the truth is the failure was going to happen anyway. But that a tranny shop falls for this c r a p, is beyond me. Maybe these guys are not so great after all.

 

I agree rall paul. Clean oil can not possibly be bad.

Ken

 

I've done the gentle flush (with engine running) 5 or 6 times on my vehicles. Twice on my Areostar--1996, V6, 128000 mi. This is what I did 2 days ago on my Mazda, 89000 mi.
Short version.....
1. Drain the pan if you have a drain plug. Refill with exactly the same amount you took out. Probably 3-4 qts.
Get the manual and find out the transmission capacity, I think my Aero is 12 qts???
2. Disconnect one of the cooler hoses. (My van and car have external coolers). You'll have to figure out which is the outlet. Not too hard---run both sides into a 5 gallon bucket and start the engine for 5 seconds. It will be obvious. Mark the bucket on the outside with a felt tip pen in one or two quart graduations (lines) ahead of time.
Have the needed number of qts ready and funnel in place on the car.
3. Start the engine and pour into the funnel/transmission about as fast as it is coming into the bucket. You can see how much you've removed as the level moves up the lines you marked.
Pour in exactly as much as you take out, up to the stated capacity in the manual.
I've heard that to make sure you empty the torque converter, apply parking brake and slowly shift thru the gear range at least once as th engine is running.
Helps to have a partner, but I do it by myself usually. If at any time you panic, stop the engine, catch your breath, and pick up where you left off. The process of running the engine and adding oil will take about 2 minutes or so.

Some people say to stop when the fluid coming into the bucket turns "new fluid" cherry red. Use tygon tubing into the bucket and you can see it better. I can't judge that well, so I remove and put in equal amounts. Fine measure what went into the bucket by pouring into the empty quart bottles you now have, unless you do a good job of marking the bucket and trust it's accuracy. Make sure you've added back only what you took out. Try to stop short of adding a quart or two. When you finally decide how much you have removed, go back and top off with the exact amount. By this time the engine will have been stopped a while. I just don't want to overfill because I don't have a plug on my transmission, so it is hard to get it out once it is in.

 

I can get 4 qts if I drop the pan, but only 3 qts if I use the plug. Last time I got 3 qts out. Started it and ran it for 1 minute and got another 20 oz out.


If I don't do the power flush I may drain the pan, then run it shifting through the gears to drain the TQ, then see if more comes out the pan. Then I will disconnect the line at the cooler and blow with bicycle pump to get more out. Maybe get enough that way, maybe not.

 

do the gentle flush after a good freeway run, 20 miles to warm up and stir up ATF

be all set up when you pull in drive.

to remove overfill, just drain a little out of cooler line

this is NOT a power flush where ATF is forced thru the lines and transmission , often backwards

 

The pan drop and filter change should be the easy part, right. It looks like there is only one bolt to hold in the filter. Is there anything special I should know about the filter change, like maybe there is an o-ring or something that could fall out and cause a malfunction?

Is the pan gasket just set in place or do they use something like Permatex to seal it?

 

Yeah, if all you got was 3 or 4 quarts, that is only about a third of the fluid in your tranny. Its not unlike doing an oil change through the oil filter, you might get 2 quarts out that way. As mentioned above, the technique we outline is NOT a power flush. We call it a gentle flush, since the only components that get stressed in any way are systems that are under constant pressure during actual operation, there is no risk to damaging the tranny from this method. But as I mentioned above, the tranny can be damaged by old worn out fluid.

 

I'm a little perplex with this procedure; cooling line is a derived circuit in the tranny: oil travel from the pump to the cooler and return into the pan. I prefer to drain the pan with a hand vacuum pump, refill with new oil, drive a mile or two, drain the pan again and refill, several time if needed with Mercon oil; converter and servos contains several liters of oil, I've seen that in disassembling my old tranny. At least I change filter ( with new O-rings) and put B&M Trick Shift oil; Real Mercon oil is unavailable here in France and what I can find is an oil meeting Mercon and Dexron specifications at the same time; Trick shift seems to be a good oil, but it is blue, not red.

 

I thought Trick Shift was Type F, the old Ford tranny fluid from the 70s.

Aerostar tranny holds 9.7 qts per Chiltons. If you are doing repeat partial changes, you generally will waste a lot of fluid after the second partial change. Here is how to calculate the remaining proprotion of old fluid on repeat partil changes:

If you get 4 qts out each time, then there will be 5.7 remaining or 63% remaining.

Remainder after each partial change:

1) 63 %

2) 40% (0.63 x 0.63)

3) 25% (0.63 x 0.63 x 0.63)

4) 16% (etc.)

So at step 3 you have used 12 quarts to replace 7.25 qts.

At step 4 you've used 16 quarts to replace 8 quarts.

I will try the tire pump hooked to the cooler line and hope to get a lot out. I suspect much will come out the pan area and some out the other cooler line.

 

Pan change flush method is a lesson in oily frustration.

Ford used our gentle flush technique in their dealer shops for years until these machine systems came out. the first ones often were hooked up backwards and high too high a pump pressure, newer machines are ok as long as the op. cleans them each use.

technique was taught to me by 35 year retired Ford ASE cert. mechanic, not one of these "it doesn't show a code on my Nintendo, therefore your car has no problem" hackers that have never had grease on their hands

would you drive your rig around with only an 85% oil change with a qt of old 100,000 miles oil left in that is oxidized badly, loaded with engine particles? more like battery acid than oil

i can do a complete ATF change in our rigs faster than a shop can with their machine

Allison and hvy equipment shops have done auto tranny changes this way for years, still no machine used in most