First,
NEVER rely on what someone tells you.
RTFM !!!
Read The FREE (F'in) Manual !
The Manual states to check your ATX Oil every 5,000 miles for signs of discoloration or burning.
If anything is found, the ATX needs servicing.
If no problems are found, service the transmission every 30,000 miles.
The ATX actually needs to be serviced more like every 12,000 miles or less.
Second,
Now that transmissions are ELECTRONICALLY SHIFTED,
service people tend to rely on the PCM for TOO MUCH INFO.
They forget aoubt doing basic ROAD TESTING, or PRESSURE TESTING, to determine the state of your transmission.
All they do his connect it to a scan tool and say,
"I don't see any codes...Nothing is wrong."
I wish I had a $1 for every time I was told that.