Automotive Transmission Fluid Change

[mean dad]

2015 GMC Terrain needs the trans fluid changed out and I'm curious about the pros and cons of doing it myself vs having it flushed and refilled at a service location.

I do all my own fluid changes on all vehicles so the work itself is no big deal. The fact that I need to drain and refill the transmission two or three times (with a few hundred miles between) means making time for the task 2 or 3 times, buying transmission fluid 2 or 3 times and frankly 2 or 3 chances to make a mess of my driveway.

Flush and refill is a one-and-done, but appears to have the risk of sediment being disturbed and causing blockage issues down the road.


What say you, BARF?

 

[i_am_the_koi]

I'm always very scared of flushing transmissions on older vehicles, 2015 I wouldn't be as concerned.

How much are they charging for the service?

 

[mean dad]

Not sure, the first place I called said they're only draining and refilling the 6 qts or so and that was $115ish.

I'm not as concerned about the cost as I am the potential for future damage. I'd rather pay to have it all flushed and refilled to save a lot of time but have no problem doing it myself if that's the best option.

 

[i_am_the_koi]

It's easy to do yourself. Since you're in there, check to see if you've got a tranny filter (you should) and replace that as well. You'll see quickly if you need to flush repeatedly or can get away with one or two passes.

My issue with the job on older vehicles has always been more that if it's not a transmission that's been taken care of, if you get rid of the fluid you get rid of the grit, and suddenly your transmission blows.

 

[msethhunter]

On my own vehicles when I was still wrenching, I'd do a fluid exchange, not a flush and a trans service to swap the filter. No chemicals. Do the trans service yourself, then tell them "NO CHEMICALS". If you do a typical service, you're leaving all the fluid in the convertor.

 

[scootergmc]

I've never "flushed" a transmission, new or old. Most I've ever done is disconnect a cooler line to get the majority of fluid out. Other than that it's usually just drain and refill. Never had a problem in hundreds of thousands of miles.

I too have heard the horror stories of something coming dislodged during a flush, but have never personally known anyone who had a problem.

 

[mean dad]

On my own vehicles when I was still wrenching, I'd do a fluid exchange, not a flush and a trans service to swap the filter. No chemicals. Do the trans service yourself, then tell them "NO CHEMICALS". If you do a typical service, you're leaving all the fluid in the convertor.

I'm not quite following you.
The procedure I'm planning on doing has me drain and refill, drive for about 400 miles, and repeat (up to three times) to ensure the majority of the old fluid has been mixed in and removed by the final drain/refill.
You're saying to do that, and then take it somewhere and have the filter replaced? What chemicals would be used and why?

I've never "flushed" a transmission, new or old. Most I've ever done is disconnect a cooler line to get the majority of fluid out. Other than that it's usually just drain and refill. Never had a problem in hundreds of thousands of miles.

I too have heard the horror stories of something coming dislodged during a flush, but have never personally known anyone who had a problem.

Yeah I haven't heard anything but horror stories (no verified accounts) but it'd suck to be the guy the guy it happens to...especially since it's the pretty thing's car, and not mine. :laughing

 

[easter bunny]

The procedure I'm planning on doing has me drain and refill, drive for about 400 miles, and repeat (up to three times) to ensure the majority of the old fluid has been mixed in and removed by the final drain/refill.

That seems incredibly overkill and wasteful if this is just a PM procedure. I tow with my car and it has a transmission notorious for burning the fluid. I drain/fill twice a year with Valvoline at $20/gallon and haven't had a single issue. Ford even calls the fluid "lifetime" without any expectation for a change. Unless you suspect an issue or really abuse it I wouldn't worry about it.

 

[mean dad]

That seems incredibly overkill and wasteful if this is just a PM procedure. I tow with my car and it has a transmission notorious for burning the fluid. I drain/fill twice a year with Valvoline at $20/gallon and haven't had a single issue. Ford even calls the fluid "lifetime" without any expectation for a change. Unless you suspect an issue or really abuse it I wouldn't worry about it.

I'd guess that your religious attention to twice-yearly fluid changes has a lot to do with the longevity of your transmission. :thumbup
I try to be as fastidious but it never caught on. :laughing


The pretty thing and I agreed that 3 times was a bit much, but changing it out at least twice makes sense to me to get the bulk of the old fluid out.
Changing it every 6 months would pretty much do the same thing but as someone once said, ain't nobody got time for that except the easter bunny.

 

[Slow Goat]

Have a ‘93 Jeep and have changed the trans fluid and filter every two years since new. Never had a problem. Also do the differential/axle fluid every five years.

An ounce of prevention and all that....

 

[rtmac]

Never flush... just drain and refill.
If the fluid is still clean-ish looking, just do it once.
If the fluid is already really dirty, do it two or three times until it's clean.
The trick is to never let it get really dirty... then it won't be necessary to do multiple drain/refills.
:2cents

 

[gixxerjeff]

What chemicals would be used and why?

He is absolutely correct on "NO CHEMICALS".
Companies such as BG and MOC partner with dealerships and independent shops and provide chemicals that they claim will "enhance/improve" on OEM fluids. They base their knowledge on "decades of scientific testing." Some of their stuff isn't all bad but some of it can be a disaster. The oil additives are the scariest to me. If their products were truly as revolutionary as they claim them to be the manufacturers that have to honor the Powertrain warranty would already be using them. The dealerships that I worked for only kept BG/MOC around for the use of their convenient service menus. Their existence in shops seems to have little to do with the quality of their additives.
Yes, just say "no chemicals please".

 

[mean dad]

:thumbup

Thanks all.

 

[nakedape]

I'm not quite following you.
The procedure I'm planning on doing has me drain and refill, drive for about 400 miles, and repeat (up to three times) to ensure the majority of the old fluid has been mixed in and removed by the final drain/refill.
Yeah I haven't heard anything but horror stories

On my Honda Civic (1993) it was refill, select through all gears, drive forward 500 yards, backwards one parsec, whatever. What you're describing is a tranny driven flush, not fluid change.

I have a horror story, and it's ongoing. The PO of our Rav decided to drop the dealer towards the end and in an attempt to get the car ready for us, had an independent "flush" the tranny. Instant slippage from 0-1000 RPM from stop. It's like a delay where you need to slowly apply pedal to assure good bite in the clutch pack.

Rough kickdown shifts at speed too but it's totally driveable. You might say, how do you know how the car behaved before? It was our friend's car and we used it several times a year for various things. Fucking sucks. You are right to be cautious.

 

[bikewanker]

I drain and add 2 quarts of ATF maybe every other year/oil change. Had either a flush or fluid exchange 154,000 miles ago cause the fluid smelled bad. Think I’ll drain and fill tomorrow, appreciate the reminder.

 

[CABilly]

Can someone explain the paradoxical effect of changing the fluid and killing the transmission? Mine are way overdue and I’ve been thinking about getting the flush at the ol stop-n-lube but if it’s gonna grenade my shit maybe I’ll just let it ride

 

[scootergmc]

Can someone explain the paradoxical effect of changing the fluid and killing the transmission? Mine are way overdue and I’ve been thinking about getting the flush at the ol stop-n-lube but if it’s gonna grenade my shit maybe I’ll just let it ride

Just google it and you'll probably end up in a Bob is the oil guy Amsoil pit of despair. Read till you're dead. Then just drain, refill, and continue on with your life.

 

[mean dad]

Can someone explain the paradoxical effect of changing the fluid and killing the transmission? Mine are way overdue and I’ve been thinking about getting the flush at the ol stop-n-lube but if it’s gonna grenade my shit maybe I’ll just let it ride

Some engine oils have detergents in them, to keep the sludge from accumulating and decreasing engine performance. Picture someone using regular oil and not changing it as often as they should, and then when they sell the car they decide to fix a decade of neglect by draining the oil and putting new oil with detergent in.
That's a lot of sludge that's gonna break loose and travel through a myriad of teeny tiny spaces that weren't designed for sludge to pass through.

That's the general idea behind the 'horror story' of a flush vs multiple fluid changes.

Just google it and you'll probably end up in a Bob is the oil guy Amsoil pit of despair. Read till you're dead. Then just drain, refill, and continue on with your life.

Or be like this guy ^^^. :laughing

 

[rtmac]

Can someone explain the paradoxical effect of changing the fluid and killing the transmission?

It fucks things up. :nerd

 

[aminalmutha]

All I gotta say is DO NOT go to AAMCO. Con artists. They will try to sell you all sorts of unnecessary bullshit and try to scare you that your car is going to explode if you don’t get said unnecessary bullshit done.