Scotty, I'm confused...
I recently acquired a 2005 Toyota Avalon with 125k miles on it. I want to take it and have the automatic trans flushed and reserviced. I've been told, "DO NOT DO THIS, IT WILL RUIN IT!!" I can't understand how fresh fluid and filter could possibly be a bad thing. I have my 2003 F150 done every 50-60k miles and after 275k miles it operates perfectly. Maybe these "Nay-sayers" used the wrong fluid?? I don't know. This just goes against everything I've ever been taught about engines, transmissions, and basically, lubricants in general. Any advice would be helpful. Love your NO B.S. videos, too!! 👍 Thanks much! Jim S.
Do not flush an automatic transmission, that chances clogging delicate areas and parts with debris and gunk that shouldn't be there. That will cause the transmission to malfunction. Do a drain and refill only, and change the transmission filter.
Fresh fluid won't ruin a transmission. If changing the fluid causes a tranny to stop working, then it was already ruined.
I've talked to several transmission guys about this now (some with generations of experience) and they think it's BS too. It's very rare for problems to happen (and we're talking high mileage trannies 200k+), and in that case they're already worn out.
I've also asked them about using fluid exchange machines ... no issues. However, they're not necessary unless the fluid is in bad shape.
I've personally done fluid exchanges on all my vehicles at close to 200k with zero problems.
I say proceed with the necessary maintenance. Drain, fill, and filter replacement should be enough.
I'm no expert, but I have watched many transmission tear-downs now, and I have never seen any debris of size larger than would pass through the filter, in the fluid. I have seen metal chunks as a result of catastrophic failure of major parts like pumps or gears (transmission dead). I have seen broken down seals (usually as a result of snake oils added by the owner). And I have seen very, very dirty black fluid as a result of abuse, and lack of maintenance. But even though the fluid was very dirty, the particles were very fine, and the fluid still flowed throughout the various valve channels and orifices. I did not see any failures that were a direct result of dirty fluid causing *blockages*. All the channels and passages are big enough for the micron size particles to pass through. The one exception was the filter. Not changing the filter WILL cause it clog up, starving the tranmission of fluid, resulting it poor or no shifting and possibly even damage..
So if my transmission fluid were very dirty, I would want ALL of that dirty fluid OUT of my transmission. Not left in it.
Bottom line. Stay on top of maintenance, and you won't be in that situation.