fluids in just about every gear case, including manual transmisions can be changed or topped off.
and yours is no different. but there are no service interval checks on that.
open the service plug (not the drain plug-so look at the manual), if fluid trickles out, you're good. other wise,
here's how to do it on a 94 toy corolla,
http://www.autozone.com/autozone/rep...00c1528006ee7d
if yours is a different model, then you need to sign up, plug in vehicle info, and go to "REPAIR INFO / 1994 TOYOTA (model and engine option goes here) / REPAIR GUIDE / GENERAL INFORMATION & MAINTENANCE / FLUIDS AND LUBRICANTS / MANUAL TRANSAXLE"
the manual is online only, and FREE.....
good luck!