RE: When to change transmission oil??
 

well there kinda is and its on the side of the tranny pan area. but its horizonta...so good luck with filling that.
people can use that as another place to see if they filled it up enough or not, because the fluid should **** right below the opening of that hole when full.
most people just put it through the dipstick.

the horizontal hole is typically used for a tranny flush via a machine.