When to Change Tranny Fluid?

[CDW6212R]

Which filter would be best for a 1990 with >150,000 miles?

Any gasket except one made from cork is fine. The others will last for ages and most are reusable.

The later transmissions I think all have rubber reusable pan gaskets. The 4R70W which is the bullet proof descendant of the AOD uses a gasket made with steel covered with rubber, they last forever. I'll be building one soon for my Lincoln.

[oldschool1]

Thank you Don.

[robertbweltzien]

Any good brand such as NAPA gold or any other premium filter from peporellauyzonadvacarquewalm etc. Don't get a cheap one. They aren't worth it in the long run. I change mine and drain the TC in my '89 LSC (if possible) every 50K or so. With 187K it shifts like a champ. In the 20 or so auto cars I've owned all but one lasted well beyond the life of the car. The one that didn't was the subject of a class action lawsuit against Chrysler (Ultramatic 4 speed in a '91 Dodge Spirit V6). With fluid changes and properly set throttle cable/rod you'll never have to worry. My '86 CV police car finally croaked at 359k but the tranny was still good!

[CDW6212R]

Any good brand such as NAPA gold or any other premium filter from peporellauyzonadvacarquewalm etc. Don't get a cheap one. They aren't worth it in the long run. I change mine and drain the TC in my '89 LSC (if possible) every 50K or so. With 187K it shifts like a champ. In the 20 or so auto cars I've owned all but one lasted well beyond the life of the car. The one that didn't was the subject of a class action lawsuit against Chrysler (Ultramatic 4 speed in a '91 Dodge Spirit V6). With fluid changes and properly set throttle cable/rod you'll never have to worry. My '86 CV police car finally croaked at 359k but the tranny was still good!

Funny Bob, I got 335k out of my first 86 CV police car. The AOD let go at 212k miles while I was delivering mail, the 1/2 accumulator came apart(steel shaft epoxied to an aluminum round piston/top). It was still going when I sold it at 335k.

[mikeceli]

rock auto .com has several to choose from. I have used Fram, ATP, Motorcraft and others. Rock has the Motorcraft FT58 w/ cork gasket (which I prefer) for $15, ATP on clearance for $ 4.05.




http://www.rockauto.com/en/catalog/linc ... ilter,8600

[CDW6212R]

rock auto .com has several to choose from. I have used Fram, ATP, Motorcraft and others. Rock has the Motorcraft FT58 w/ cork gasket (which I prefer) for $15, ATP on clearance for $ 4.05.




http://www.rockauto.com/en/catalog/linc ... ilter,8600

I see that the choices for a pan gasket are slim from typical sources, those all look like cork gaskets with the filters. I've bought that Ford part a couple of times, and tossed the gasket in the trash both times. I think what I have came from a master rebuild kit from Level 10 performance, probably around 1997. The rubber or reusable gaskets may only be available from aftermarket companies, not the Dorman type replacement makers. I'd say the online transmission parts sources should have the better pan gaskets, I'd expect them to cost close to $10-15 just for those. But those will last forever, and don't need sealant either. Happily my 4R70W's all came from Ford with a metal/rubber gasket, and they do last forever. Fumbling with a cork gasket that doesn't want to lay flat or stay in place while you start the bolts is bothersome. The rigid type are a breeze to use.

[mikeceli]

I find the cork seals better. Cork has become very expensive, hence more synthetic AT pan pan gaskets available.

[90 MarkVII BB]

Is there any merit in the theory that if you don't know if the fluid has been changed regularly, that it may be better just to leave it since new fluid may be more slick and therefore result in more slippage, therefore, more wear?

I've always wondered this. Also, how the hell would you get it out of the torque converter?

[CDW6212R]

The deal there is with very old fluid, if enough material(debris) has accumulated in the valve body, it's kind of stable(bad but spread evenly), and new ATF will likely move some around. If it stays evenly suspended, and passes out, no problem. But if it concentrates anywhere and causes a valve to move differently(slower), shift timing will be affected.

If any debris causes any malfunction of the valve body, bad things will happen(various symptoms). The material I'm talking about is very very fine, it gets through the internal filter, and it travels until it reaches a slow moving spot, and settles. Old fluid is less likely to keep that material moving, new ATF is excellent at "cleaning" even though it isn't really a detergent.

So if new ATF is followed by a bad symptom, it is not the fluids fault. There was already bad things inside the trans, the VB specifically. A little accumulation won't hurt most of the rest of the trans, the clutch drums being the next possible sensitive areas. But the VB is super important to all functions, any malfunctions caused by debris usually will end in a failure of something, clutches slipping being the most logical.

Here's what I conclude from those facts; if the old fluid appears relatively good and clean, I want to change it all, and accept the slight chance of something being in the VB that ends badly. If the old fluid is clearly dirty, than I'm scared to do either, and neither choice is good. That's when you have to choose carefully, do nothing and hope, or do something. If it's a trans I'm comfortable with, I'll install a VB kit, which requires the VB to come out. Then I can look it over well, and clean it if I think it needs that.

[robertbweltzien]

Even though my AOD lost OD, I did routinely drain the pan and TC every 50K. I think you guys are right that it simply wore out from 195 K miles, leaving 1,2 and 3 OK. That seems to be its Achille's Heel. I always drove the car for at least 10 miles before servicing in order to suspend the contaminants in the fluid before draining. Of course, when the OD went south, the fluid had turned black. Still, the fluid change stopped the delayed 2-3 shift. Had I not serviced the AOD regularly, I believe the car would no longer be drivable.

Oh and hats off to Don and oldschool1 et al. for the informative write up on building a strong AOD. Credit also to our mentor, the late Mr. Art Bailey.
The Duralast kit from Advance Auto, TF-132, has a reusable nitrile gasket.

Bob