transmission flush or just fluid change?

If cost is an issue, there is certainly nothing wrong with Mercon.

thanks for the links and all the good info!!!!

I will probably just flush it for now, and change the filter and add the aux. filter later.

aldive said:

It is best to drop the pan ( at least once ) and change the filter, Refill with ATF of your choice and then do the following flush procedure:

I disconnected the "to transmission" hose from my remote filter housing. I plugged and clamped the disconnected line and added and hose clamped a 6 ft length of 3/8? line to the housing. The other end went into a calibrated water jug ( 1 gal size ).

The the truck run at idle while 1 quart is pumped out. Stop the truck andd add back 1 quart of new ATF.

We used 15 quarts of Amsoil ATF.

Even though this ATF ( Amsoil ) has about 40 k miles on it, it still looked remarkably good, just slightly darker in color.

After the flush/fill was completed, I added a new K & N filter to the housing and reattached the hoses.

The procedure took my son and I about 15 minutes to complete. There was no mess since we were well prepared for the flush; nary a drop was spilled.

Click to expand...

When you do this do you have the truck in drive or park?

And being that I have a 4r70w with a 14qt cap. How many quarts do you think I'll need to complete this process, filter change and all?

302Xplorer said:

When you do this do you have the truck in drive or park?

And being that I have a 4r70w with a 14qt cap. How many quarts do you think I'll need to complete this process, filter change and all?

Click to expand...

It doesn't matter what gear you're in when flushing, except that if you're in drive the truck might move! I'd put it in park. The idea is to pump it out, and the only requirement for that is that the truck is running...

For my truck it pumps out 1 quart every 7 seconds; I used milk jugs marked with quart lines.

It will probably take 20 qts to flush it PROPERLY. You can get by with less but your fluid may not be totally clean. You flush till the fluid coming out looks as clean as what's going in. Might take 16 qts, might take 22 qts.

If you're cheap like me, you can put in cheap mercon for the first 3 or 4 quarts and then start putting in the good stuff (Royal Purple, AMSOIL, Mobil 1, whatever you plan to run).

the idea is that the first few qts you put in will get pumped out again anyway, so you might as well use cheap stuff for that.

Just make sure that QUARTS GOING IN = QUARTS THAT WENT OUT. If ya do that you won't have any underfill/overfill problems.

I do my flushes in Park.

Filter change and flush are also a part of the whole process. Although, getting it all performed by a well qualified transmission repair specialist is much reliable and would definitely last for a long run.