2015 -Transmission fluid Change Vs Flush

tcooll77 · Feb 2, 2018

2015 silverado 1500
78K
Highway miles- use truck for hunting trips.

The place that changes my oil ( i live in and apartment) said i need to get a "transmission flush"

I am fine getting these services done but from the little i know about vehicles i have heard it is more favorable to just change the trans fluid as opposed to flushing it.

any advice on this would be appreciated.

thank you
tim

esox07 · Feb 3, 2018

Without a flush, you won't get all the fluid out. That being said, many owners do the pan drop and filter change even though they only get a bit over half the old fluid out. There are reasons for doing this rather than a flush. First and foremost is that a flush does nothing to the old filter. It is like changing motor oil and leaving the old filter on. As a transmission is used, the clutch plates and such accumulate particles which the transmission is used to running with. If you remove all the old fluid and these particles, it could cause the transmission to have issues. This is especially an issue with a transmission that hasn't had it's fluid changed for a long time (say over 100,000 miles). Therefore, many feel that more frequent pan drops and filter changes are the better way to go.
It is much easier for a shop to hook your truck up to a tranny flush machine, let it run and fill it back up and send you on your way with a $250 bill. You can do your own pan drop and filter for about $50 and have the satisfaction of knowing that it was done right.

Here is a how to for the 2007-2013 trucks on a pan drop and filter. I don't know how close it is to the newer trucks. The trick is getting enough clearance between the transmission and exhaust pipe to be able to drop the pan. It might be a bit better engineered on the newer trucks.

HOW TO - Pan Drop and Filter Change on GMT900 4x4 Six Speed

With your driving conditions, I think your owners manual states that you are good for about 100,000 miles. Either way you decide to go, I would probably do it sooner, so now is good. I personally do my pan drops and filters at about 40,000 mile intervals. I don't take my oil changes to the GM recommended interval either.

Z15 · Feb 3, 2018

Here is a GM procedure for trans flush from a technical service bulletin for 2015 8-sp. Note-The 8-sp does not have a dipstick.

This was done to my 2015 truck and then a new torque converted was installed. I had them install AMSOIL Signature Series Fuel Efficient ATF when they changed the torque converter later on.

umwolverines · Feb 3, 2018

Don't listen to em. With a flush you're not changing the filter, which is pointless. Even if you don't want to drop the pan and change the fluid and filter yourself, it will be a fraction of what they want to charge for a flush. And personally I wouldn't go there to do it. I don't trust places that recommend services that aren't necessary.

esox07 · Feb 3, 2018

Z15 said:
Here is a GM procedure for trans flush from a technical service bulletin for 2015 8-sp. Note-The 8-sp does not have a dipstick.

This was done to my 2015 truck and then a new torque converted was installed. I had them install AMSOIL Signature Series Fuel Efficient ATF when they changed the torque converter later on.

Yah, that sounds like a great plan. I wonder just how many do both together. I asked my "Service Manager", not a tech, but manager about a tranny service. He quoted me about $250 for a flush. I asked him if that included a new filter and he said: "Your truck has a screen, it doesn't have a filter" so, no, no new filter. That is why I say, if you do it yourself, you know it is done right. How can they do it right it they don't even know my truck has a filter?

Also, if you look close at that TSB, it looks like it is designed for a truck that is experiencing a "Shudder" which is the reasons for a double pan drop and flush. I don't think that is the "normal" flush procedure.

ASTE25 · Feb 3, 2018

I would just do a drain and fill with a filter change. I am not a fan of the flushes.

Welcher774 · Feb 4, 2018

I have seen both done. When I was in the shop if the vech had less than 100k would do a flush mait only. If someone came in asking for flush would quiz as to why they asked. Questions like any shifting issues, noises,etc or for maint. Would explain it is a maint only service. NOw if the pan was leaking would change the filter and gasket.

If the fluid was burnt smelling and really dark without having service done would not suggest flush. The flush machine uses the truck trans pump'to pull in nee fluid while it pushes out the old. If a lot of junk in the fluid it is possible to have issues afterward. Hope this helps.

08_AllTerrain · Feb 11, 2018

With that many miles I would never recommend a flush. Unless you've done regular transmission service since day one you never want to do a flush. Personally I would do a drain, filter change, and fill. If you're not experiencing any issues currently a drain and fill is all you need.

lbf · Feb 12, 2018

These flush services are a money making up-sell for the shop.

The "how to" up there in the second post gives you everything you need.

IMO, changing the fluid without the filter is a waste of time and money.

lbf

OrdieJay · Mar 8, 2018

I'm on the change the filter side. I don't see why changing fluid without the filter is worth the time. Dropping the pan and wiping all the crud and shaving out is always good.

JOEC · Mar 9, 2018

Just did a pan drop and filter change today. Hardest part was getting the exhast out of the way of the pan. Otherwise quite a painless exercise and nothing better than clean fluids!

esox07 · Mar 9, 2018

Joec: Did you replace the filter seal? IF so, how did you get the old one out and new one in?

JOEC · Mar 9, 2018

I did not. My consensus (from reading lots of opinions and experience on other forums )was that those typically do not wear out and therefore (this time around- first change) I'll leave the old filter gasket in. I did however replace the pan gasket.

JOEC · Mar 9, 2018

Some pics from today. The trans fluid shower was fun.

esox07 · Mar 9, 2018

Yah, I will be doing my second one this spring and figure I should probably replace it this time. I went and bought the 3/4" threaded pipe today. I hope it works. And I hope I dont have trouble getting the new one in.

Oh, and yah, It is virtually impossible to drop the pan without spilling a good amount of fluid. Did you siphon any out through the dip stick tube before you dropped the pan?

Also, how did you pull the exhaust down to get clearance for the pan?

Oh, did you do the differentials and transfer case as well?

JOEC · Mar 9, 2018

I did siphon with a pump kit I have. Very handy.

As far as the exhast, I put a jack with a chain to pull down the exhast like another member here had done in the past. Worked ok. Ended up jamming my leg into the chain for more leverage and voila!

esox07 · Mar 9, 2018

Yah, that is how I did it in my HOW TO. I was just wondering if you did it another way. I could see the chain on the exhaust in one of your photos..

Tatsngats · Mar 9, 2018

I didn't replace the filter gasket when I did mine either. No problems. I don't see how that thing could wear out. If you guys end up replacing yours I'd like to see how.

mikew · Mar 9, 2018

To get my exhaust out of the way I used a stiff crowbar, one end on top of the pipe, used the frame as a fulcrum with jack on other end of bar.

hot2na · Mar 9, 2018

wonder if a 2017 will be any different with pan clearance issues?

ferraiolo1 · Mar 9, 2018

If it's the 6 speed then it's the same as a 2014+. If it's a 8 speed then it's a different ball game.

Sent from my iPhone using Tapatalk

JOEC · Mar 9, 2018

esox07 said:
Yah, that is how I did it in my HOW TO. I was just wondering if you did it another way. I could see the chain on the exhaust in one of your photos..

Thank you very much. Your post was most helpful.

2015 -Transmission fluid Change Vs Flush

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