The gear oil for a 1996 Chevy Cavalier Z24 manual transmission goes into the
transmission case itself. There's a fill plug and a drain plug on the transmission. The fill plug is usually located on the top or side of the transmission case, and it might be a slightly different size than the drain plug. You'll need a shop manual or a reliable online resource with diagrams specific to your year and model to pinpoint the exact locations of these plugs.
Caution: Before you start, be sure to consult a repair manual specific to your car's year and model. This will show you the exact location of the fill and drain plugs, the type and quantity of gear oil to use, and the proper procedure for changing the oil. Using the incorrect oil or procedure can damage your transmission.
