Transmission fluid flush with filter change

[HiHoeSilver]

When do you drop the pan and change the filter?

Most guys will pump out a bunch first, say 4-5 quarts. Then drop the pan and do the filter. Reinstall, add fluid, and continue pumping and adding until its clean. Then top it off. If you're a guy who only wants his new filter to see new fluid, pump and fill until it runs clean first, then pump out the 4-5 quarts.... Blah blah. You obviously will go through more fluid this way.

 

[chevy529]

Is there a general consensus as to whether a "full" flush should be done at all?

There seems to be two schools of thought on this.

Some say just do a pan drop\filter change.

 

[Chubbs]

The pan drop and filter replace is generally considered the safest method for high mileage vehicles with an unknown service history and/or delayed service, especially if the TF in question appears to be burned up, off-color, bad odor.

A full flush with commercial equipment & detergents/chemicals usually added is definitely not safe for the above described conditions and is only prescribed for those transmissions which have been serviced per factory guidelines, low mileage & lack of wear & tear. TF that qualifies for this regiment still appears like a brand new fill, where one is replacing it well before the end of its useful service life. This would be the best case scenario and one that everyone adheres to but we all know it's not like that in the real world.

The tranny and transfer case in my mothers 2004 Tahoe just grenaded this last weekend with I don't know how many hundreds of thousands of miles. Hasn't been serviced since she bought it less than 1-year old. That 4x4 prob could have kept on commuting the remainder of her working life had she changed the fluids AT LEAST once; too bad we will never know. It's going to the junk yard. She did change the motor oil regularly but engine alone doesn't make a daily driver!

The first thing that I do after purchasing a 100,000 mile vehicle is replace most if not all major fluids ASAP. I've had this last 1 maybe 8-months and all I have left is the brake fluid (replacing by end of May) and coolant which looks healthy, anyway. Everything else was done within first 2- months for preventative maintenance & so as to provide a stable platform for system's operations.

Imagine how many vehicles on the road with 200,000 miles and still on the original power steering fluid... That shit breaks down from time & heat and becomes contaminated with bits of material from the hoses, metals from the pump & gears. Chemicals don't last forever; maintenance costs money but failures from lack of maint costs much, much more.

 

[chevy529]

The pan drop and filter replace is generally considered the safest method for high mileage vehicles with an unknown service history and/or delayed service, especially if the TF in question appears to be burned up, off-color, bad odor.

A full flush with commercial equipment & detergents/chemicals usually added is definitely not safe for the above described conditions and is only prescribed for those transmissions which have been serviced per factory guidelines, low mileage & lack of wear & tear. TF that qualifies for this regiment still appears like a brand new fill, where one is replacing it well before the end of its useful service life. This would be the best case scenario and one that everyone adheres to but we all know it's not like that in the real world.

The tranny and transfer case in my mothers 2004 Tahoe just grenaded this last weekend with I don't know how many hundreds of thousands of miles. Hasn't been serviced since she bought it less than 1-year old. That 4x4 prob could have kept on commuting the remainder of her working life had she changed the fluids AT LEAST once; too bad we will never know. It's going to the junk yard. She did change the motor oil regularly but engine alone doesn't make a daily driver!

The first thing that I do after purchasing a 100,000 mile vehicle is replace most if not all major fluids ASAP. I've had this last 1 maybe 8-months and all I have left is the brake fluid (replacing by end of May) and coolant which looks healthy, anyway. Everything else was done within first 2- months for preventative maintenance & so as to provide a stable platform for system's operations.

Imagine how many vehicles on the road with 200,000 miles and still on the original power steering fluid... That shit breaks down from time & heat and becomes contaminated with bits of material from the hoses, metals from the pump & gears. Chemicals don't last forever; maintenance costs money but failures from lack of maint costs much, much more.

I wonder if time is as big of a factor as mileage. I bought my Father's 2004 Yukon with 60000 miles and have been thinking I should replace ALL the fluids. Mainly because it sat un-driven so much. I did engine immediately, T case a month later along with the rear end. I'll do brakes when it warms up but was waffling on whether to do the TF. It smells\looks fine. I've heard so many horror stories of people's trannys failing after changing ALL the fluid it makes me pause.

 

[Tonyrodz]

I wonder if time is as big of a factor as mileage. I bought my Father's 2004 Yukon with 60000 miles and have been thinking I should replace ALL the fluids. Mainly because it sat un-driven so much. I did engine immediately, T case a month later along with the rear end. I'll do brakes when it warms up but was waffling on whether to do the TF. It smells\looks fine. I've heard so many horror stories of people's trannys failing after changing ALL the fluid it makes me pause.

I think alot of people have problems when they do the trans flush. Alot of guys recommend just dropping the trans pan and doing the filter and fluid that's in there if the maintenance history is unknown.

 

[Shaw520]

I've heard so many horror stories of people's trannys failing after changing ALL the fluid it makes me pause.

I think in most cases these are situations where the owner is already experiencing tranny issues and they think a tranny flush or fluid change is going to help,... Ive never heard of a healthy tranny going after a fluid swap. I have a ritual of changing every fluid in the every vehicle I buy,..(i never buy new),... never have I experienced an issue by swapping out fluids,.. if anything im sure it has contributed to the longevity I have been blessed with from each vehicle Ive bought and sold.

 

[Chubbs]

I wonder if time is as big of a factor as mileage. I bought my Father's 2004 Yukon with 60000 miles and have been thinking I should replace ALL the fluids. Mainly because it sat un-driven so much. I did engine immediately, T case a month later along with the rear end. I'll do brakes when it warms up but was waffling on whether to do the TF. It smells\looks fine. I've heard so many horror stories of people's trannys failing after changing ALL the fluid it makes me pause.

The transmission will not abruptly begin to fail if you replace the fluid. It's a myth and/or one-sided information provided by people who don't know what they are talking about, or @Shaw520 expressed, underlying symptoms/full-flush, etc.

The trans fluid in that truck is going to be organic-based, of which time is just large a factor of its degradation as heat is. The fluid has outlived its useful service life, period. Continuing the use of the current transmission fill is actually detrimental to the trans function. Remove the sump, replace the filter and gasket, reinstall pan. Refill with Delco IV synthetic, 5 quarts more or less.

The trans fluid draining & replace is a PIA, for which I can provide some very useful tips as result of my own somewhat recent experience. You may even find a drain bolt on the sump but any optimism for its usefulness may be ill-conceived. Ask me about that when you get to it. In essence, Not cut & dry exercise but absolutely necessary to the performance and life of the unit. 2 or 3 weeks later you have the option to replace the TF fluid again, this time via the cooler as you are not replacing the filter again. This method results in less of a mess and raises the percentage of the synthetic fluid content in the system to the ratio of the +\- (4)quarts original fluid that remained in the torque converter/pipes/cooler after the sump R&R, if that makes sense. (Pan drop, filter replace only removes 1/2 TF fill)

 

[Shaw520]

My procedure goes like this; Bring engine up to operating temp. Remove trans line from the radiator place in drain pan, start truck and idle just till the first couple air bubble come from the line, shut engine down. Remove tranny pan and thoroughly clean, remove filter and replace, re-install pan with new gasket, ad 5 quarts of synthetic atf,...run at idle once again till fluid runs clean from trans line, re-install trans line and top off required amount of fluid. With this procedure im usually able to swap out about 11 -12 quarts.

 

[chevy529]

I think alot of people have problems when they do the trans flush. Alot of guys recommend just dropping the trans pan and doing the filter and fluid that's in there if the maintenance history is unknown.

And therein lies my problem. I'm NOT a mechanic but I've pulled a lot of wrenchs in my past so I like to think I have some common sense. If all the oil within the transmission system didn't circulate you'd cook it pretty quick.

So the people saying that pushing all the oil out of the system would\could deposit debris throughout the system, bringing about its demise, makes no sense to me. If there were debris in the system getting past your filter it would be failing anyway.

So why NOT remove ALL the oil? Just makes sense to me. But maybe I'm missing something.

I'd never do it myself anymore as I'm old and lazy and don't have the tools\space to EASILY do it. I'm talking air tools. Like I said, I'm lazy.

EDIT: Does anyone know the capacity of the transmission to do a full oil exchange? Or where to find the info? TIA

 

[Teeroy78]

And therein lies my problem. I'm NOT a mechanic but I've pulled a lot of wrenchs in my past so I like to think I have some common sense. If all the oil within the transmission system didn't circulate you'd cook it pretty quick.

So the people saying that pushing all the oil out of the system would\could deposit debris throughout the system, bringing about its demise, makes no sense to me. If there were debris in the system getting past your filter it would be failing anyway.

So why NOT remove ALL the oil? Just makes sense to me. But maybe I'm missing something.

I'd never do it myself anymore as I'm old and lazy and don't have the tools\space to EASILY do it. I'm talking air tools. Like I said, I'm lazy.

EDIT: Does anyone know the capacity of the transmission to do a full oil exchange? Or where to find the info? TIA

Hi Shannon,

It varies depending on which variant of the transmission you have, but the information is right there in your owner’s manual. Mine is a 2009, and I have the six speed. I believe yours is still the four speed, so I won’t give you my capacities, but in the manual under the “Capacities and Specifications” section it is listed along with engine oil, fuel tank size, etc.