^ this is how it used to be done when one was able to tap into the ATF cooling line. With CX5 it is not possible.
The only option you have is to change the fluid several times to get to the happy point of new vs old.
You don't want to shock the transmission with a bunch of new fluid.
I used to think the above was bulls***, and would argue and argue that the transmission was not a fish, and the fluid was not aquarium water. After killing multiple transmissions because of fluid changes though, I digress. DO NOT SHOCK THE SYSTEM! I personally am against changing it at all. As the mechanic who warned me about it before each of mine had issues because I had the fluid changed (not flushed, drop/filled, AT THE DEALER), "if the fluid is bad, the clutches are already having issues, and changing it is going to introduce a different friction coefficient as well as much more concentrated/new detergents, and you will sludge up the valve body/it will die like a dog. If the fluid is not bad...you don't need to change it anyways".
Again, I called bulls***, because I was a young man with a college degree and he was just an old guy with a lazy eye who puttered around and talked about his race-cars in the 70's (that ran 11's, seen the timeslips and photo-albums, btw...), and the world had moved on from his glory years, and surely he was ignorant of the way things are NOW...but I got my plate of crow 3 times in a row before I stopped coming back for more.
1) 1988 Mustang GT. Ran fine with the old fluid in it. Old as hell, got it back in 2005ish. Changed the fluid...DEAD. Would not hardly shift out of first unless I redlined it and backed off and did all sorts of nonsense.
2) But the 1988 GT was an old car...and now I had an Infiniti G20, true, it had 110K miles on it, but the fluid looked good, it shifted great, never had set up, what could be the harm? Infiniti dealer did the fluid drain via pan drop. 5K miles later, it was the same as my Mustang GT, except it had OBDII, and it was throwing tq converter codes, slippage codes, and all sorts of crap. Dead as a dog.
3) Well those two cars were older, and had higher miles. Now I had a 2010 Grand Jeep Cherokee (in 2014) with only 68K miles, and the service interval was 60K miles. Surely THIS ONE would be fine to change fluid on! ITS EVEN IN THE SERVICE MANUAL! Well...it wasn't. I ended up with a tq converter shudder that was new after the fluid change, and never really went away.
Also of note) I had a 2001 WS.6. Surely manuals are fine to change fluid in, right? No. It never shifted the same again. I should have left the 75K mile fluid in it.
Here is the list of cars that I got better performance of/shifted and worked smoother after changing the fluid in: