Transmission fluid

So I have a 2008 tacoma 4.0. It has around 117k miles and I don't know if the transmission fluid has ever been changed or not but I noticed a slight leak by one of the hoses leading to the trans cooler and I was thinking about taking it in to be looked at and have a transmission flush done but heard people say not to do that since it's old and could cause problems. My question is how to I go about filling/checking my transmission fluid since these trucks don't have a stick. Can I just add fluid until it comes out of the overflow plug? Don't know a whole lot about this any tips would be helpful thanks.

 

Here's a couple threads on the subject. There are others as well. I did a drain, refill before dropping the pan to clean and replacing the screen/filter. IMO - a flush could create problems you don't have. The drain & refill is a safe way to service your transmission.

https://www.tacomaworld.com/threads...e-2nd-gen-transmission-pan-and-filter.726329/

https://www.tacomaworld.com/threads/how-to-drain-refill-automatic-transmission.63851/

If you tow often you may also think about an aftermarket trans cooler.

https://www.tacomaworld.com/threads...l-toyotas-write-up-with-many-pictures.526283/

 

This lady knows her stuff the video is very helpful.

https://youtu.be/ej_6BZpK3gg

 

^ I don't watch "All girls garage", but I can watch her videos. Yes, she does know her stuff!