Some Odd AT advice
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Cargo Master
Joined: Apr 2003
Posts: 3,476
Likes: 224
From: Frequently frozen MN
Some Odd AT advice
Can't remember exactly where I saw this, but somebody wrote in to an auto forum that their local lube joint said that his AT fluid was going bad ( burnt). They recommended a complete flush and fill -- total fluid change
The reply came back from someone claiming to be a mechanic. More or less 'Don't bother, it's already too late. The old fluid has left varnish deposits. New fluid will loosen them and make things worse'' Then advised him to do things right after he finally had the tranny rebuilt.
As I recall, the site seemed reputable.
I've never heard advice quite like that. I know that when the fluid gets really bad, there's likely some severe damage, but I've never heard anybody saying that a fluid change will make things worse.
Just curious if this makes sense to anybody.
Thanks,
ford2go
The reply came back from someone claiming to be a mechanic. More or less 'Don't bother, it's already too late. The old fluid has left varnish deposits. New fluid will loosen them and make things worse'' Then advised him to do things right after he finally had the tranny rebuilt.
As I recall, the site seemed reputable.
I've never heard advice quite like that. I know that when the fluid gets really bad, there's likely some severe damage, but I've never heard anybody saying that a fluid change will make things worse.
Just curious if this makes sense to anybody.
Thanks,
ford2go
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,738
Likes: 2,667
From: SE Florida
I've heard that many times. I don't believe it's true, but I can see how some people would believe it.
Many people never change their trans fluid. When the trans starts to have a problem they go to have it changed. Soon after the trans dies. That does happen. The reason it happens is that the trans was already destroyed before changing the fluid. The burnt fluid showed this. Changing the fluid won't fix a dead trans. It would have died without the new fluid, too.
Many people never change their trans fluid. When the trans starts to have a problem they go to have it changed. Soon after the trans dies. That does happen. The reason it happens is that the trans was already destroyed before changing the fluid. The burnt fluid showed this. Changing the fluid won't fix a dead trans. It would have died without the new fluid, too.
Hotshot
Joined: Feb 2004
Posts: 11,697
Likes: 3
From: Marengo, Iowa
The other thing that tends to happen is that the varnish and sediment deposits that were staying put inside the fluid circuits will come loose with the new detergents in the new oil, so it can cause some problems. It is not guaranteed to do that, but it is a possibility. Thing is, I tend to gamble on getting it changed vs. leaving it with bad oil. If it fails, then so be it. If you don't do it, it may well fail anyway.
Post Fiend
Joined: Jun 2001
Posts: 5,228
Likes: 5
From: Running Springs CA
Heat does not just damage the fluid. A lot of critical parts in an AT are not metal. If servo seals harden, which can sometimes just take one severe overheat episode, the trans will fail. Also, wear particles from clutch plates in the oil may seem to tell you the oil is burnt, but it is really just dirty from burnt clutches. Maybe a fluid flush might clean out the last bit of crud holding pressure in the servos after the seals are bad.
Jim
Jim
Hotshot
Joined: Feb 2004
Posts: 11,697
Likes: 3
From: Marengo, Iowa
Generally, the servo seals are teflon, but the clutch pack seals are rubber. if they get hard or crack, the clutches don't get squeezed as well. which leads to slipping, more heat and wear, and then failure.Removal of the varnish can lead to the clutch pack pistons not sealing, and sometimes the servos as well.Either way, if the trans is there already, failure is imminent anyway, fluid change or not.
