Why so much attention toward ATF color?

[The Critic]

We expect engine oil to discolor during use, so why can't the same be expected for ATF?

I pull dipsticks from Hondas w/20k miles and the ATF is golden honey. Yes the red dye is gone, but what's the problem? Why is so much focus being placed on the red color?

 

[ConfederateTyrant]

Perhaps it is due to all the quicky lubes, dealers, shops, etc. that see an opportunity to make commission. This seems to be where most lubricant rumors begin, as I have noticed.

I personally believe the feel/smell of the fluid would be more important than how it looks. As a gritty feel and burnt smell is not something I would want circulating through my transmission.

 

[psudaytona]

The color was seen as the indicator as to the life left in the fluid. The dyes are placed there so they lose color as they reach certain temperatures. The longer they stay at those "high end" temps, the more they lose the color. I guess the analogy was,

"Heat kills the fluid over time, so if this dye is set to responde accordingly, it will tell someone that when your fluid goes red-light brown- dark brown, its time to change it."

The transmission I am workin on now originally had +3 fluid which is bright red when new, this stuff is DARK brown(as motor oil) and smells highly burnt.

Some other fluids lose their color just naturally and its not the end all indicator of service life remaining. I would say if the fluid itself seems good, as in not burnt, no particles, or other troublesome evidence, that all is good. Providing of course the transmission is running smoothly.

 

[The Critic]

Many of the newer transmissions run extremely hot, so perhaps this explains this gradual and rapid color loss of the fluid. At the same time, while the color does indicate fluid oxidation, aren't these newer fluids able to resist/survive more instances of high temperature exposure in comparison to older fluids, hence making the fluid color deceiving as to the true condition of the fluid?

 

[gtx510]

From what I've read about ATF+4 they say not to go by the smell or the color of the fluid. Even fresh stuff smells horrible.

I thought ATF+3 was the same?

And ATF+4 is synthetics but ATF+3 isn't? Is that correct?
Or are both synthetic and ATF+4 is just slicker?

 

[alreadygone]

I would think that fluid specs would require dies to be commesurate to expected temperature.

By the time fluid smells, FEELS??, or has visible suspended particles,,,it's too late to bother with a change!!

 

[The Critic]

Most manufacturers that subscribe to this theory make it quite clear that the dye is not permanent, but whether or not techs outside of the dealerships are aware of this is a different story. So I think manufacturers really don't care about the color.

I've seen many six-cylinder Hondas with golden or light brown, "clean" smelling fluid, with no particles, in less than 30k...

 

[Ken2]

ATF contains no detergents, and transmissions do not have products of combustion. It should not get dark. Dark colored ATF is a sign that the fluid has oxidized and is no longer providing the protection is must provide.


Ken

 

[The Critic]

Wait a second. Says who that ATFs do not contain any detergents? They contain minimal detergency, but are not highly detergent.

So, if what psudaytona said was correct, the dye is lost after repeated, prolonged exposure to high operating temperatures causing fluid oxidation. But since the newer fluids are much more "withstanding" and "resistant" to fluid oxidation, mere prolonged exposure, resulting in the loss of red dye, may not illustrate the point in the fluid's lifecycle?

 

[psudaytona]

Pretty much. ATF+4 in particular is held up by its makers as a "lifetime fill" where ATF+3 never was. Using it in even extremely demanding tests have proven it to be a tough little fluid. ATF+4 has a VERY strong smell, some have described it as "baby poop" in smell. I dont know about that since I am only in college and have no children

nor do I hang out with alot of infants.

As The Critic said, ATF has a small amount of detergents in it, not to deal with combustion by products but to act to counteract the aging of fluid that could result in varnish or gunk type build ups. It keeps the build up suspended in the fluid and takes it to the filter to be captured. This is now less of a concern with modern synthetic based fluids as they are not as heat sensitive and thus less prone to thermal breakdown, much like motor oil.

I think the new fluids are colored red nowadays mainly as an idiot proofing measure and for "old skool" folks who are used to red ATF fluid. Modern synthetics are generally so tough, that if you turn ATF+4 fluid brown and burnt.....my hats off to ya. You are one hardcore driver!

 

[unDummy]

Smell and color real mean nothing without a used oil analysis.
Regardless of smell or color, I haven't seen too many good ATF used oil analysis.
Either used oil analysis it or practice more frequent ATF change intervals.

Here what needs to be known: what red dye is being used? and the temp that causes it to break down?
And, other things to consider: what happens to the red dye when it breaks down? What does it turn into? what does it clog or coat?

And, as always, if you believe that color is meaningless, prove it to yourself by used oil analysising your ATF and posting a clear glass picture of that fluid(especially if it is brown, golden, or not red). I think that you'll be surprised at how poorly your ATF is performing.

And, install a temp gauge. You might actually be able to adjust your driving style to reduce the temp spikes that cause your ATF, its color, and your transmission, from breaking down!

 

[thrace]

In my case the color change with time and miles is not loss of pink color. It is dark nearly black colored fluid that still has some pink tinge after 10-20k miles. It smells bad compared to new fluid. '02 Honda Odyssey, ATF Z1 exclusively. That can not be good.