We have a new 2016 F350 with the 6.7 in our family. It is a month old and has 10k miles on the odometer with 80% of that towing over 14k and the rest at around 6-8k. The fuel filter has already needed to be replaced due to the whining noise some have posted about.

So, we are doing the OCI at 5k and were wondering if we should increase the frequency of the transmission flush?

If so, is there a procedure similar to the one for the 4R100 in the 7.3L?

Also, Schaeffers is one of the preferred choices in the 7.3L forum, what is the preferred brand here in the 6.7L community?

 

I've got roughly 350,000 miles behind a 6.7 with almost all of it towing something and I have never had any transmission work done of any kind. Every time I check the fluid it looks and smells like new. Every time I ask someone's opinion they tell me "don't waste your money".

If your fluid looks or smells off I would stick with the motorcraft fluid.

 

No, there is not, because there is no effective way to flush this trans yourself. The ONLY way to get a flush done is with a heated flush machine. Heated flush machines are very rare, even at a dealer.

 

Thank you, sir! I lived in Greenwood about 25 years ago. I went through there about 6 months ago and it has changed...




Mark! What a pleasant surprise. I did not know that you hang out here too or I would have PM'ed you. Thank you, as always, for the precise answer I was looking for.

I still can't rep you...

 

So it is not possible to disconnect the fluid line returning to the transmission and drain the fluid that way? Of course I would be adding equal amounts through the dipstick at the same time.

 

That depends on what you mean by possible.

You can do that, and fluid will come out, and eventually you'll get the total amount of fluid out. But it won't replace the old fluid, it will mix the old and new, and replace the mixed fluid.

The older 4R100 did not have a thermostat. The fluid flowed to the cooler all the time. Starting (at least in the trucks) with the 5R110 there is an internal thermostat. Until the trans warms enough to open the thermostat 90% of the normal flow to the cooler is diverted and does not go to the cooler, it's recycled inside the trans.

So as you open the cooler line you get 10% old fluid coming out. Now as you add fluid to replace the 10%, it is mixed in the pan with the old fluid already there.

The only way that I know around this is to get the trans hot (at least 170°F) and connect it to a heated flush machine to prevent the trans from cooling off during the flush.

 

Thanks for the information. My current truck doesn't have a thermostat in the transmission so doing a full flush with the return line is easy.

 

Wow

Mark, hypothetically, assuming that there is a thermistor that reports resistance to the PCM or whatever commands the valve to open & close, if one were to find out the the resistance at say 180*F, could you fool the computer into opening or closing the valve w/o frying something either through tuning or a physical resistor? Or is it more complicated than that?

 

No, that won't work. The thermostat is very similar to an engine thermostat. It's a wax pellet, there are no electronics involved.

 

Thank you for the information.

 

Correct me if I'm wrong, I don't have my manual in front of me, but isn't the trans fluid change interval for the 2016 something like 150k miles?

 

And there's no easy way to drain the torque converter while doing a filter change to try and get the majority of old fluid out before a refill is there?

 

There are only two ways to get the fluid out of the converter. Either use a heated flush machine, or take the converter out and dump the fluid out of it.

 

How much does a full fluid flush with a heated flush machine run? It sounds expensive.

 

Ok. Thanks