Transmission Fluid Flush sequence?
 

So I'm not really flushing the transmission, but I'm going to be doing the fluid/filter on my '15. I've got 107k miles on it, and in the last month I've had the transmission squawk happen a couple times. I'll also get the TSB done soon for the hard downshift/squawk.

Anyway I know when you drop the pan you're really only changing about 1/3 of the fluid out. So I'm thinking I'll pump out and refill using a fluid pump a couple more times other than the pan drop. My question is would you start the fluid swap before you put in the new filter or after? Or does it really even matter?

My first thought was do do the pan/filter first, then a couple more fluid pump/fill a week or two afterwards, but then I thought I'll be running all that old fluid through the filter for a while.
Second thought was to start swapping fluid out, then put in a new filter, but then you're running new fluid through an old filter for a while.

Or am I just way overthinking this and that it really won't matter at all?

the filter really isnt a filter..its just a screen. Change it, drive the truck a mile or two. then drain the fluid again

Ok, good point. Would you drop the pan again or try to pump it out?

i would drop the pan..or when you drop it the first time, put a drain plug in it

If you have a cooler, there is a way to tie into it as well. My Chevy, in tied into the cooler and pumped out, then dropped the pan to clean magnet and change filter. Bolt pan back up and fill, then start and let the pan get sucked up and the old to continue pumping. I did this until new fluid was being pumped oit. I'm not sure if I'll do the same process as I'm not sure where the feed is from tranny to cooler so I may just use the mighty vac to suck most out, drop pan and clean with new filter then fill and then in a few thousand, do it again since I'm sure my fluid is mostly good since it has 32k on it but many of those miles are hard pulling miles so that's why I'm doing it so early.

My pin TSB was done so they removed and added 7qts but not sure they did the filter per the workup.

The process isn't hard at all looking at the ford. Chevy had the exhaust right under the tranny pan making it impossible to get it out without major unbolting or exhaust or tranny. That was the only hard part.

OK so your 15 has the ZF 6sp trans in it. It like the newer models - is designed to be flushed with a big machine that has the multi-pass filters in it.

Get it flushed - save your efforts.


If you drop the pan - and I'm not against it much - biggest thing you will do is clean the bottom of the pan. The filter as said before is a mesh screen - and replacing it would get rid of big pieces if there were any in there - you'd already know.

Flushing gets more of the fine particles out and the bulk of the worn off clutch materials. It also replaces 90 or so % of the total fluid ammount in the device. This is the biggest benefit. SO I suggest flushing it at some place with the right machine - like the dealer or a reputable transmission shop.

Thanks, I'll check it out and see what they get for it, probably a good idea.

Typical PISS POOR GM engineering!

I've heard bad things against reverse flushing so stay away from that. Most mechanics suggest a pan drop and filter fluid change. I've read stories of higher milage vehicles getting a flush and then needing a new transmission after. The small particles that were on the filter were dislodged and we're sent through the system.


it's also expensive to get done and it's not that hard. Do it yourself and it's rewarding and you learn your truck a little more. I do pay to get things done that I can do myself.

I've never changed plugs until yesterday and it was easy and cheap!

I don't mind doing it myself, I just thought it would be wise to get all the fluid out instead of just 1/3 to 1/2 of it...