I would cahange it at 50,000 miles.
It does not have a timing belt, it has a chain.
To change the transmission fluid on your Chevy Malibu 2005, first, pull off the pan, drain the fluid, and replace it.
There should be two dipsticks under the hood on a Malibu. One will be plainly marked "OIL" or "ENGINE OIL." The other one is your transmission fluid. This is assuming your Malibu has automatic transmission. If your Malibu has a manual transmission (stick shift), then there is no dipstick for transmission fluid -- manual trannies get lubrication from the engine oil.
Auto.? dipstick at rear of engine Std.? should be a plug at the side of transmission
Dexron
Dextron
If it is an automatic it should have been done sooner.
You can tell if the transmission, in your 1998 Chevy Malibu, is going bad. If there is a whining or clunking noise. The transmission might cause your engine to install when you are stopped with your foot on the brake.
Check your transmission.
Dexron VI
9 liters
A 2004 Chevy Malibu uses standard Dexron III transmission fluid. This is a widely available fluid used by many GM vehicles.