Chevrolet 1993 Astro Passenger Owner's Manual page 257

To get the right reading,
the
fluid should be at normal
operating
temperature,
which is 180°F to 200°F (82°C to
93°C).
To check transmission fluid hot: Get the vehicle warmed up by driving
about 15 miles (24 km) when outside temperatures are above 50°F (10°C). If
it's colder than 50°F (lO'C), drive the vehicle in
D
(Third Gear) until the
engine temperature gage moves and then remains steady for ten minutes.
Then follow the hot check procedures.
To check transmission fluid cold: A cold check is made after the vehicle
has been sitting for 8 hours or more with the engine off and is used only as
a reference. Let the engine run at idle for 5 minutes if outside temperatures
are 50°F (1 0°C) or more. If it's colder than 50°F (lO"C), you may have to
idle the engine longer. A hot check must follow when fluid
is added during a
cold check.
To check the fluid hot
or cold:
Park your vehicle on a level place.
Place the shift lever in P (Park) with the parking brake applied.
With your foot on the brake pedal, move the shift lever through each
gear range, pausing for about three seconds in each range. Then,
position the shift lever in P (Park).
Let the engine run at idle for three minutes or more.
Then, without shutting off the engine, follow these steps:
K3619
6-21