Manual Transmission refill GL4 99 Sephia

[jackc146]

My son recently drained the transmission oil on his car. He asked where is the fill Dad. I said I don't know. I searched on this site and found what I thought to be confusing answers. I took out the 10mm bolt on what I believe to be the speed sensor. I couldn't get it to budge after that. Question? What needs to be done here? Do i need to use channel locks to remove it. Can I use 80 -90 gear oil. If so, do I fill the transmision thru speed sensor hole and continue reinstalling l using the gear as and indicator thats it's full when it shows oil. What steps need to be taken as to not cause additional problems when reinstalling. This seems crazy. Any help would be appreciated. Thanks