Why ATF D&F might be better than full exchange.

[TrevorS]

Seeing that changing engine oil too often could be a bad idea because detergents strip the anti wear layer before the new anti wear layer can begin to protect, could full ATF exchanges create similar issues?

Could ATF detergents result in reduced protection right after a full change?

Might Drain and Fills be a better approach?

I'm also thinking that UOAs could be very helpful here.

 

[GutsyGecko]

No. How would you feel about leaving 3/4 of the dirty engine oil in your sump? My opinion anyway.

 

[cb_13]

Idk about just a straight fluid exchange but I have heard many horror stories about the chemical flushes on high mileage transmissions. Of course the snake oil companies will blame lack of previous maintenance and that is a valid point but for me a simple pan drop, filter change and refill is the way to go. I am interested to hear the opinions on this one though.

 

[901Memphis]

You do not see the Moly/Titanium anti wear additives that are present in motor oil in ATF, so i don't think its the same type of anti wear layer being stripped.

 

[Donald]

Originally Posted By: 901Memphis
You do not see the Moly/Titanium anti wear additives that are present in motor oil in ATF, so i don't think its the same type of anti wear layer being stripped.


+1

The D&F uses significantly more ATF to get to 90-95% than does a cooler line exchange.

If you are just looking for a "refresh" of the ATF, not an exchange, then a &F might be reasonable.

 

[mclasser]

Honda's official protocol for a "flush" is a 3-time D&F. I've always been wary of power flushes. Doing a full exchange using the cooler lines is certainly the most efficient since you replace all the fluid at once. Personally, I just prefer the good old D&F method.

 

[Jim Allen]

Originally Posted By: TrevorS
Seeing that changing engine oil too often could be a bad idea because detergents strip the anti wear layer before the new anti wear layer can begin to protect, could full ATF exchanges create similar issues?

Could ATF detergents result in reduced protection right after a full change?

Might Drain and Fills be a better approach?

I'm also thinking that UOAs could be very helpful here.


No. The chemistry of ATF is vastly different than motor oil and they don't have nearly as many detergents nor anti-wear additives but a lot more FMs, some esters and other stuff that motor oil doesn't have.

I'll say it again. I think D&F are a viable maintenance tool ONCE THE INITIAL LOAD OF BUILT-IN AND BREAK-IN CONTAMINANTS HAVE BEEN ELIMINATED BY FILTRATION OR A FULL FLUID CHANGE. Once this has been done, the D&F reduces the level of normal wear contaminants (which is created in vastly less amounts than during break-in) and replenishes the base oil and additives int the remaining oil. I still think additional filtration and a longer OCI followed by a fluid fluid exchange as warranted by oil condition (oxidation, etc.) is the best idea long term.

 

[Donald]

Originally Posted By: mclasser
I've always been wary of power flushes.


Can you provide an example of a "power flush"? I was not aware a "power flush" existed.

 

[cronk]

A "power flush" is when the trans cooler lines are disconnected and hooked into a machine. The machine basically consists of a tank with a diaphragm or bladder in it. The tank is filled with fresh atf, and when the vehicle is started, the old oil being pumped through the cooler lines by the transmission pump goes into the tank and push's on the diaphragm and forces the new atf out the other side of the tank where it goes back into the transmission by the other cooler line.
We had one at the Nissan dealer I used to work at and it was a pretty neat piece of equipment. Very simple but effective.

 

[FutureDoc]

The downside to a flush is that all fluid is passed through the filter before it is on its way out... while anything in a pan could be removed with a D&F especially if the pan is removed. So normal flushes only get "filtered" ATF. Those power-flush machines can be slick but if done incorrectly or in a non-compliant/compatible manner, it can cause problems.

D&F are a bit more fluid intensive but is the least amount of risk to a transmission. Flushes can be fine, use less fluid, but be careful in case you do not have enough fluid on hand or something happens to the feed. It might also benefit form a new filter, but if you have to drop the pan to get to it, might as well do a D&F. Power flushes are unnecessary, more risky, and is just a tool to make a shop look better.

 

[tommygunn]

ATF changing is mostly about heat and thermal breakdown, isn't it? That is why changing isn't really that counterproductive even if it may still be a waste of money.

However, I'd never get a machine flush for the ATF because they force stuff through and could clog something in the trans. Also, most of the power flush machines overfill by at least a quart or two.

Just drain through the drain plug. If your car doesn't have one, then get an aftermarket transmission pain that does have the plug.

 

[Donald]

Originally Posted By: cronk
A "power flush" is when the trans cooler lines are disconnected and hooked into a machine. The machine basically consists of a tank with a diaphragm or bladder in it. The tank is filled with fresh atf, and when the vehicle is started, the old oil being pumped through the cooler lines by the transmission pump goes into the tank and push's on the diaphragm and forces the new atf out the other side of the tank where it goes back into the transmission by the other cooler line.
We had one at the Nissan dealer I used to work at and it was a pretty neat piece of equipment. Very simple but effective.


I already knew what it was. The dealer may call it a "power flush" to get extra zing out of the service but in reality its no different than the cooler line exchange I can do since both use the transmission's own pump to pump the ATF through the transmission. A "fluid exchange" machine would be more correct, but less zing in the marketing message.

 

[KrisZ]

Originally Posted By: mclasser
Honda's official protocol for a "flush" is a 3-time D&F. I've always been wary of power flushes. Doing a full exchange using the cooler lines is certainly the most efficient since you replace all the fluid at once. Personally, I just prefer the good old D&F method.


Since Honda has troubles with making a reliable AT, when others don't, why would their "protocol" be any indication of one method being better than the other?

 

[Russell]

my shop does a D&f on my BMW which includes blowing out the cooler lines and cooler. Not 100% exchange but seems to work well. I do it every 25,000 miles.

 

[FutureDoc]

Originally Posted By: KrisZ

Since Honda has troubles with making a reliable AT, when others don't, why would their "protocol" be any indication of one method being better than the other?


Part of the problem is that people do not service their Honda transmissions and think neglect is "fine" because Hondas are reliable. The other issue is that the old Z-1 fluid was not that good... and more extreme change interval might have been better for it (15K rather than 30K). The DW-1 is better. A 9 Qt D&F got a fraction under 90% of the old fluid out from my Honda.

Finally, Honda really needs to figure something out about the V6 and their tranny. There is definitely something wrong there.

 

[Vikas]

There have been enough cases of people who were more than religious about their Honda V6 transmission (regular d&f every other oil change, inline filter, cooler etc) but still lost the transmission at around 125K.

 

[Russell]

Originally Posted By: Russell
my shop does a D&f on my BMW which includes blowing out the cooler lines and cooler. Not 100% exchange but seems to work well. I do it every 25,000 miles.

Forgot to add, my 4-speed auto made by GM in France for BMW failed at 211,000 miles. For the record it's first trany oil D&F was at 85,000. Also for the record, this is known to be a weak trany. Many fail with less than 100,000 miles.

 

[surfstar]

All my vehicles are manuals, so I don't have to worry about stuff like this