Discussion Forum - Northstar Chevelle Club

Jon H · 1K+ Club

Change or flush modern transmission fluid???

Chris R · 2K+ Club

At that mileage. I would drop the pan and change the filter as well.

Lost in the 60s · President

Jon H wrote:
I have a 2010 Tahoe with 67,000 miles on it. I am trying to figure if I should drop the pan, change the fluid that comes out and change the filter OR do a flush. I have read to flush between 50-75,000 but only change the filter and fluid that drains at 100,000+. The theory is that flushing a high mile tranny will dislodge built up dirt and cause more issues. Any recommendations?

Jon, I went thru this with mine last week. I was quoted $180-200 for a filter change and flush. I had changed the filter and the 3 quarts in the pan at around he same mileage you now have. The fluid still looked good at that time. I beat the heck out of my trans pulling my 2 ton truck back from Pagosa Springs CO 2 years ago a camper trailer to Deadwood SD last fall and that was most likely a contributing factor in my fluid now looking and smelling slightly burned.

This time, I pulled the drain plug intending to just change the 3 quarts but it smelled too bad for that. I dropped the pan to see if there was anything in it and was relieved to see it was still clean. I changed the filter anyway and refilled the pan. I then drove the truck around the "block" until warm and pulled the drain plug and refilled. I did this 3 times to exchange as much of the 12 quarts it holds for a "flush" effect. The fluid is now the correct transparent pink and smells like fresh fluid. The cost for a NAPA filter kit was $28 and 12 quarts of fluid @ $5 each was $60. Much less than taking it somewhere and I know what's been done...

For your truck, I would recommend dropping the pan to see if there is any unwanted debris inside and add new fluid. If the fluid is still clean and doesn't smell burned, I would drive it for another 20k miles and drain the pan again.

NAPA does sell the fluid in a 5 gallon pail for $60. You can disconnect the cooler lines at the radiator and extend them with hoses to the pail and another catch pail. Start the truck and let it run until you see clean fluid coming out of the hose. That is the same flush I was told would be done to mine by one place. Others have a pressure machine, but I have doubts it will really get all the fluid exchanged if the engine isn't running and powering the pump.

SShink · 3K+ Club

Jon,

Two options that I suggest:

1. Give our buddy John a call at Master Trans, and get his recommendation. He won't steer you wrong.

2. Kennedy Transmission has a location in Forest Lake that I think is near you? And, they have an on-line coupon right now for a trans service or flush for $69.95 + $5 for Trucks ($30 Savings). I've gone to the one in Apple Valley before I discovered Master Trans, and David Kennedy was as straight a shooter as John at MT.

I used to change my own tranny fluid on our daily drivers, but it's not worth the time, mess, and lying under the car IMO when the cost of the materials is higher than finding a special like Kennedy's and having them do it. Just my .

Stan

Chris R · 2K+ Club

John. Are you back here in the cities yet or are you looking at doing this down south? Im thinking you might have to call around down there to local shops and get a feel for whom might be best to have it done. I agree though, for 150-200 dollars, it might not be worth it to do it yourself. However, I do believe that truck takes Dexron IV fluid which the last I checked, isnt cheap so you may not find a place that would do it that cheap.

bowtie · Secretary

Option C: Ask your future son Mike what he thinks? He's (or was) a decent tech. I know the idea behind the pressure machines is to evacuate as much of the old fluid as possible.

Lost in the 60s · President

You guys are forgetting 2 things;

1) Jon is retired and has all kinds of time on his hands...

2) He's cheap....

dashboard · 2K+ Club

Cheapest place to buy Dexron IV fluid is Wal-Mart. Take it somewhere to have it done and enjoy your time in the sun!

Jon H · 1K+ Club

Where to start.
I have talked to John at MT, my future son-in-law (a GM tech), and others. There does not seem to be a consensus, that is why I started this thread.
I am still on vacation so either I cough up the dollars here or wait and either pay or do it my self at home.
Yes the Dextron is spendy but necessary. I was more interested in the theory than the cost.
And yes Mitch I learn from the best.
Thanks to all.

67ss · 1K+ Club

My wifes subaru had 308,000 when we sold it and I never once dropped the transmission pan on it and only drained and refilled the fluid every 30,000-45,000 miles. But I will say subaru uses a mesh screen type filter and not a paper one like most and they did not recommend to replace it. My wifes current Jeep has 180,000 plus on it and at every 30,000-45,000 I do a fluid exchange with a machine and have dropped the pan only twice to replace the filter on it. I know the newer fluids have a longer life of supposedly 50,000 so the intervals could maybe be extended. If you don't tow with it and it is just a driver I would do an exchange on it and do the filter at 100K like you stated.

John D · 2K+ Club

I can see the thought behind the theory of a flush-job dislodging "crud" in a older gearbox... you are cycling a bunch of fluid through the system.

Given a choice, I'd drop the pan and change the filter. This way I get a look at how much residue (clutch dust & metal) is in the pan. You can unstick the magnet & get the metal & clutch dust out of the pan (what would be the crud that gets dislodged).

THEN have the system flushed. Any remaining crud from the hydraulic circuits and converter would then be trapped on a clean magnet and new filter.