I would not recommend additives that chemically alter the transmission oils properties. But there are other more effective solutions that can accomplish the same thing, aka Hydrogenated DLC coatings. Some auto manufacturers are using vapor deposition methods to coat rubbing pairs with hydrogenated DLC coatings from the factory, however once those coatings wear off, they gone for good. Not only is it expensive and time consuming, but it has limited life span in an engine or transmission so it's only used in specific applications by OEM's.
That's where an In Situ Hydrogrenated DLC coating (Synthetic Magnesium Silicate Hydroxide) comes into play. You can achieve super lubricity as well as high levels of anti-wear properties by using this:
https://shop.tribotex.com/products/transmission-automatic
If your skeptical, I CHALLENGE you to come up with more testing and validation than what I have provided on this technology below (I have more if you really want to dive deeper yet). I've been using in a 2012 Prius C I got used with 80k, a 2016 modified Mustang GT 5.0 that makes 480 HP with just a Ford Performance Power Pack 2 and TriboTEX (the power pack 2 is rated for 455 HP and the engine stock was 435 HP) and now on a 2018 CX-9 with about 33k on clock.
There are engine, automatic transmission, manual transmission, transfer case / diff formulas that vary by concentration of the synthetic MSH. My ONLY caution is that during the wear in process for automatic transmissions or bikes with wet clutches, you do not want to do any towing or constant full throttle / hard launches, if it forms on torque converter lock up clutch disks or your wet clutch during the wear in phase, your transaxle or wet clutch will slip constantly until it wears off = not good!
It is considered a PERMANENT coating and will typically last about 80,000 miles in an auto-trans and around 40k in an engine, however if you have a track car like my 2016 Mustang GT was that sees constant high RPM 4,000 to 7,100 RPM, I would expect to replace it at half that interval in engine applications.
Remember this is NOT an oil additive, it is an In Situ Hydrogenated DLC coating that forms via Heat and Pressure on wear surfaces over hundreds of miles of use (typically around 500) and is considered permanent (no way to get it off except via wear and tear). It does NOT alter the oils chemical formula, it only uses the lubricant as a carrier to the contact sites during the wear in process.
Of particular interest for transmission applications is the Weveden Hypoid Gear Oil test, it is THE MOST gruelling gear oil test, if it passes this with flying colors, it's a good lubricant with strong EP additive capabilities. Also note that hydrogenated DLC coatings promote better oil adhesion, which means it allows you lubricating oil's hydrodynamic film to support higher loads before it collapses into mixed mode or boundary layer lubrication regimes than what the oil could support on bare metal or zinc tribofilm coated rubbing pairs.
Also of note is that MoDTC (organo-molybdenum) additives reduce the wear rates of hydrogenated DLC films, so for engine applications it's even more beneficial to run motor oils that have MoDTC additives.
I generally do NOT recommend oil additives because if the formula gets too out of whack, you can increase friciton and wear instead of reduce it! You can also adverse affect the hydraulic properties in a negative way by accident, unless you understand the chemistry, your simply playing Russian roulette with chemicals.
In only recommend this technology because I actually HAVE the research behind, how it works, how it interacts with common motor oils formulas and additives etc. along with documented testing.
I would reccomend fresh fluid then add TriboTEX automatic transmission formula, then at your next oil change add TriboTEX standard engine formula. During the wear in, just drive the car normally.
Benefits of In Situ Hydrogenated DLC Coatings:
1. can be applied to existing technology without disassembly / rebuilds
2. can be re-applied once the coating wears off without disassembly.
3. the film wears off, not the surfaces of the rubbing pairs
4. can compensate for some surface wear by covering the surface asperities (aka roughness of the surface due to wear) via building up layers of worn rubbing pairs up to several hundred microns
5. achieves super-lubricity of rubbing pairs
6. a newer anti-friction additive called MoDTC developed by Infinium in 2009 is highly beneficial for the life of hydrogenated DLC coatings, essentially TriboTEX will last longer when pairing it with motor oils containing this organo-moly anti-friction additive that is now in many motor oil formulas
7. reduces oil consumption by creating a better seal between the piston rings and the cylinder wall
8. more power to the wheels by reducing lost energy to friction (in all application areas)
9. not susceptible to water absorbption like MoS2 or Hexagonal Boron Nitride where they can actually become abrasive, thus increasing friction and wear (hence why MoS2 is used in axle greases still but not in motor oils, CV axles are sealed via the boot, so no moisture can enter, not so with an engine during heating and cooling cycles, humid / wet driving conditions etc.)
Downsides
1. Long wear in process of around 40 motor hours or approx 500 miles
2. Cost, it's a bit pricy but has some significant benefits. There's an old adage however that GENERALLY remains true in most situations, you get what you pay for!
3. In applications of torque converter lock up clutches or wet clutchs, if subjected to heavy use (drag launches, towing or frequent heavy throttle use) during the wear in process of the gears in the gearbox / transmission, it may form on the disks causing slippage. However I have not seen any reports of that issue in auto trans, but TribTEX does give that warning for bike applications.