Auto transmission service schedule?

[RamblerGuy]

Originally Posted by babock

Not only do I change every 30K but I do a full fluid change.

1) Drop the pan.
2) change filter and refill with 3 qts ATF
3) Pull the return line off the radiator or tranny cooler and run a clear hose into a container marked for 2 qts.
4) Run engine until you hit the 2 qt line.
5) Add 2 qts fluid
6) Repeat steps 4 and 5 until the color of the fluid in ow new looking.

Replacing just the 3 qts in the pan is just going to allow you to dilute some of the 12 or more qts of fluid that is in the entire transmission.

When I changed the fluid in our Ford E450's 5-speed transmission, I drained eight quarts out of the pan. The Ford shop manual says it takes 19.2 quarts to fill an overhauled transmission and convertor. Ford only recommends draining the pan and changing the filter. They don't say it needs to be completely flushed.

[babock]

Originally Posted by RamblerGuy

Ford only recommends draining the pan and changing the filter. They don't say it needs to be completely flushed.

You get way more of a percentage out than most transmissions. Personally, I like changing out all the fluid rather than just diluting the old fluid.

[18CrewDually]

Originally Posted by babock

Not only do I change every 30K but I do a full fluid change.

1) Drop the pan.
2) change filter and refill with 3 qts ATF
3) Pull the return line off the radiator or tranny cooler and run a clear hose into a container marked for 2 qts.
4) Run engine until you hit the 2 qt line.
5) Add 2 qts fluid
6) Repeat steps 4 and 5 until the color of the fluid in ow new looking.

Replacing just the 3 qts in the pan is just going to allow you to dilute some of the 12 or more qts of fluid that is in the entire transmission.

I do almost identical service every 30k miles. Doing this method on my Ford is the difference of 6 qrts. doing a drain and refill compared to 16-18 qrts. blowing out the cooler and running it to push out the old fluid.
Yes more time and money but in the long run it potentionally saved me $5k in repairs. I now have 178k miles and I tow heavy alot (12k-25k#s + truck is 9,850#s)

[campsmith1]

After just having my transmission rebuilt the shop recommended I changing fluids yearly if towing a lot.
After what I spent think I'll have to go with what they said.

[18CrewDually]

Originally Posted by campsmith1

After just having my transmission rebuilt the shop recommended I changing fluids yearly if towing a lot.
After what I spent think I'll have to go with what they said.

If you're towing at or over the limits of a gasser SUV then I would follow those recommendations too. Heat kills which it sounds like you may of found that out the hard way.
A properly cooled trans that only sees 180-200°f, 30k miles interval is recommended but 15k is better. At 15k it's usually not wore out but instead a drain & refill is to get rid of all the suspended contaminants.