How do you replace tranny oil in 1989 Mazda b2200?

Answer 1

underneath the transmission is a bolt that will drain the fluid (it will be the only one on the flat under side. it is best to have the vehicle level to do this and while the transmission is still a bit warm.

let it drain fully while it does this take a chance to clean as much crap off the magnetic end of plug

replace the bolt and put in a new copper washer (you can get value packs from most auto stores)

now remove the square bolt on the left side of the transmission and use a hand pump or such to fill the transmission with API GL-4 SAE 75w-90 or 80w-90 transmission oil until it starts to leak out the hole and replace the plug

some people opt to remove the gear stick and pour the fluid into the top of the box from inside the car. i think it's worth buying a $20 hand pump to avoid having to pull the whole console apart.