Transmission fluid

[85MercPark]

I am planning to change my transmisson fluid.
I searched and couldn't locate any information

My dipstick says Dexron II

I have about 5 qts of Dexron III sitting in my garage and a couple Type Fs.

Are the compatible?

Any suggested types?

How many qts?

My fluid still looks red, but my intermitent overdrive loss makes me want to change the filter.

[Tiggie]

Mixing Dextron III/Mercon (replaced II) and Type F isn't like mixing oil and water. They will mix uniformly. But they are still different. Type F has added friction modifiers made specially for older Ford tranny's, like the Ford- and Cruise-O-Matics and C4's and C6's.

In the old days, people would run Type F in GM tranny's to make them shift firmer and generally better all around from a performance standpoint. But I wouldn't put it in an AOD.

Loosing OD occasionally isn't good. Sounds like a rebuild is coming soon.

If you drain the torque converter and pan, you're looking at about 12 quarts. Just the pan and filter is about 4-5 quarts if I remember correctly.

Get a case of Mercon (not Mercon V) from Ford.

[85MercPark]

Ok, so Dexron III replaced Dexron II. No wonder I couldn't find it

[gadget73]

Once in a while you'll find bottles marked Dex/Merc III and it says on the back that its compatible with transmissions that want Dex II, but not always. But yeah, Dex/Merc III is what you want for an AOD. You can use Merc V, but I probably wouldn't suggest it in a used trans. If its a fresh or very low mileage transmission perhaps but on a 21 year old, it might clean it out so well that it stops working.

I'm also thinking you might want to start saving up for a rebuild. When they start popping out of overdrive it usually means the band is worn out. The earlier trans had a smaller overdrive servo, and poor lubrication in the tailshaft of the transmission, which would cause premature gear failure. Larger OD servo ( B vs the C) came in 86 I think and the rear lube mod was 1988. They can be retrofitted fairly easily though. The earlier trans also had a 3-4 accumulator that would sometimes stick and cause the overdrive band to wear faster. They actually eliminated this totally on later transmissions, which is a big part of the 3-4 clunk that the AOD has. Nothing to soften that shift.

[gadget73]

Once in a while you'll find bottles marked Dex/Merc III and it says on the back that its compatible with transmissions that want Dex II, but not always. But yeah, Dex/Merc III is what you want for an AOD. You can use Merc V, but I probably wouldn't suggest it in a used trans. If its a fresh or very low mileage transmission perhaps but on a 21 year old, it might clean it out so well that it stops working.

I'm also thinking you might want to start saving up for a rebuild. When they start popping out of overdrive it usually means the band is worn out. The earlier trans had a smaller overdrive servo, and poor lubrication in the tailshaft of the transmission, which would cause premature gear failure. Larger OD servo ( B vs the C) came in 86 I think and the rear lube mod was 1988. They can be retrofitted fairly easily though. The earlier trans also had a 3-4 accumulator that would sometimes stick and cause the overdrive band to wear faster. They actually eliminated this totally on later transmissions, which is a big part of the 3-4 clunk that the AOD has. Nothing to soften that shift.

[85MercPark]

It only acted up that one time when I was towing, I would slide it up into OD on down slopes only.

Near the end of the trip I slid it in OD and nothing happened. Once it cooled down it has shifted fine.

I only have 46000 on this transmission

[gadget73]

Not supposed to be towing in overdrive. Tsk tsk!

[Lincolnmania]

the 85 aod has the weakest overdrive servo.....the c servo.........if you are towing in overdrive you need to have an a overdrive servo installed....if it's not too late....i'd suggest getting ahould of brian........46,000 miles doesent mean shit......the car is 22 years old....has the fluid ever been changed? do you have a transmission cooler?

[85MercPark]

Yea, my bad. I was only in OD when the hills where big enough that I didn't need to give it any gas, I guess even that was too much. It is ok right now, hasn't acted up since July so keeping my fingers crossed. If it goes I will just get a good one built by Brian.

I will need one for sure once I do the conversion to HO.
Can that OD servo be installed alone without major teardown??

Yes fluid was changed before I bought it at 26000 miles.

Yes, have a transmission cooler

[Lincolnmania]

needs to be torn down to replace the overdrive band.......good idea to replace the clutches and seals and to update the valve body when the trans is apart

[85MercPark]

Well, let's hope this one holds on until I can afford to do it right.

[Pirate]

Once in a while you'll find bottles marked Dex/Merc III and it says on the back that its compatible with transmissions that want Dex II, but not always. But yeah, Dex/Merc III is what you want for an AOD. You can use Merc V, but I probably wouldn't suggest it in a used trans. If its a fresh or very low mileage transmission perhaps but on a 21 year old, it might clean it out so well that it stops working.

I'm also thinking you might want to start saving up for a rebuild. When they start popping out of overdrive it usually means the band is worn out. The earlier trans had a smaller overdrive servo, and poor lubrication in the tailshaft of the transmission, which would cause premature gear failure. Larger OD servo ( B vs the C) came in 86 I think and the rear lube mod was 1988. They can be retrofitted fairly easily though. The earlier trans also had a 3-4 accumulator that would sometimes stick and cause the overdrive band to wear faster. They actually eliminated this totally on later transmissions, which is a big part of the 3-4 clunk that the AOD has. Nothing to soften that shift.

Completely off-topic sir, but after noting your double-post, does your computer hang up a moment when adding longer replies to this forum? I can't seem to make a reply in under 20,000 words, and it takes forever to get the site to accept it....shorter replies go a hell of a lot faster, and if I click 'reply' too many times, I get double posts in a row....

[gadget73]

Completely off-topic sir, but after noting your double-post, does your computer hang up a moment when adding longer replies to this forum? I can't seem to make a reply in under 20,000 words, and it takes forever to get the site to accept it....shorter replies go a hell of a lot faster, and if I click 'reply' too many times, I get double posts in a row....

once in a while. Usually if it does that, I click 'go advanced' and it works. I have no idea why it does that, seems to be some gremlin ever since the vb 3.6 upgrade but I haven't got the slightest clue why or how to fix it.

[86VickyLX]

I always get the flood control message

[Nathan in MI]

once in a while. Usually if it does that, I click 'go advanced' and it works. I have no idea why it does that, seems to be some gremlin ever since the vb 3.6 upgrade but I haven't got the slightest clue why or how to fix it.

Mine does that every once in awhile, too. Like you said, just click "Go Advanced" and then it goes immediately. I figured it was just me lol