Howdy Scotty?  I'm here in the Philippines, and I just viewed a few of your informative & entertaining videos on You Tube, thank you very much for the global community service you provide, in helping novice mechanics like me, make wise car maintenance decisions.

I run a 2011 Isuzu Alterra (aka MU-7) diesel, it has about 70,000 miles on the clock.  I have changed its a/t fluid every 15 to 20k miles consistently.   Its transmission requires Dexron III fluid.   I would like to change from the mineral based a/t fluid to a synthetic fluid.  A friend of mine whose auto advice I respect, said it's best to change the transmission filter and change the fluid from a mineral based to a synthetic, run it for a few thousand miles, and then change the fluid again using synthetic, for changing from mineral to synthetic based will cause any gunk or dirt in the transmissions crevices to flush out.   Now this seemed like quite an undertaking, and I wanted to ask you if this was really necessary, especially since I have consistently changed the a/t fluid on a regular basis?  I've observed my mechanic allowing the a/t fluid pour out, and sure it's a bit dark, but still quite red every time he's changed it. 

Thank you for taking the time to answer my question. 🤩 

All the best,

Carlos