I have an s2 tranny (out of the car) that I need to fill with fluid. I really dont want to buy a $10 17mm allen socket. On the TOP of the tranny there is a black-capped hole - the air expansion hole I am told, but to the right of that is a 17mm bolt/plug that has a spring inside. Can the tranny be filled through this hole?

 

just buy the cheap $10 allen socket. its $10.you use the filling plug as a level to fill the transmission up to

 

If you are dead set against buying the $9 wrench, take a 17mm head bolt with a couple of nuts jammed on it. use a 17mm open end, problem solved the cheap way

 

My problem is not really buying the allen (I can spring $10) my question really is since I have the tranny out can this CONVIENT big bolt/hole on TOP of the tranny be used to fill it up?

 

Buy the wrench, use the proper fill hole.

 

You could probably fill it that way, but when will you know you've added the proper amount of fluid? IIRC, you want to fill it to within a couple mm below the real fill hole.