I can certainly identify clearly with the opinion of "linkwitsync" - I too have had issues in the past with flushes; however, I was usually flushing a transmission that had 60 or 80k miles on the clock (being a buyer mostly in the used market in my earlier years). That being said, since 1998 I have bought only new cars - and if I am the one taking care of the vehicle, then I DEFINITELY recommend changing the fluid - and doing so via a flush (I did mine at Valvoline) at a minimum every 50k miles. I do my fluid flushes every 30k miles because I drive in the city a lot. I would recommend doing a filter change at 100k miles because they do have to take some stuff apart (not sure what, but it's not ridiculous like having to unbolt the transmission - that's crazy), but just keep flushing between now and every 100k.
In our 6F50's (and 6F55 for the EcoBoost group), the whole deal with Mercon LV (low viscosity) is that its viscosity rating is about 5.9 versus the 7's or maybe 8's of other traditional transmission fluids. I have done research on this extensively, and found that the Valvoline Global ATF fluid is indeed LV-compliant because it is (1) full-synthetic, and (2) its viscosity is also rated at 5.9; so, I felt very comfortable flushing with that fluid as opposed to going to the actual Lincoln-Mercury dealer to do a Motorcraft Mercon LV flush. That being said, it is likely that some of the "friction modifiers" - the special sauce - between the Valvoline and Mercon LV aren't identical, so just keep that in mind; however, I can say that having 10k miles on a Valvoline Global ATF flush with my 2012 MKS has been trouble-free and I'm more concerned about the fluid being clean rather than it identically matching down to the molecule.
Now, what is interesting about the "LV" fluid is that it appears to oxidize more quickly than a more highly viscous fluid; however, the clear upside of using this fluid is that its lower viscosity allows for faster fluid flow - especially in the cold weather, not only enabling better fuel economy due to less viscous resistance, but much quicker lubrication over the moving parts. So, to me, a fluid like LV or Valvoline Global Multi ATF is well worth all the trade offs. The nice thing is, we have standard oil cooling on the D3 platform with trans cooler lines running through the bottom of the radiator (the cooler end of the radiator), but if you wanted you could potentially upgrade that cooling setup via the aftermarket - just make sure to add more fluid if your aftermarket cooler is bigger than factory - but you know that.
I have used Dash Command on my OBD-II sensors around the vehicle, and I can say that I have not seen the transmission temperature go above 170F in city driving; I have not done this test on a long trip, however - so that means this transmission isn't a hot-runner (I have the 3.7L FWD), and maybe because it's 'ready' for AWD, I honestly don't know - but I didn't see that temp go above 170F -- maybe if it's 98F outside, and I'm sitting a while in traffic - I'll have to test it this summer and find out.
As for flushing - if you are not comfortable with flushing, then definitely go to a dealer (or only a very trusted shade-tree guy/gal who knows 6F's to have the trans service completed); and you can expect to pay about $120 for a shade-tree guy/gal or $250 for a dealer, including the filter change.
I love this transmission, even if the coasting-fuel-cut-off program likes to fight with me for control over the unit; but hey - my heavy foot wins that fight every time...
Edited by email@example.com, 07 April 2017 - 09:40 AM.