Service Intervals: Transmission
WARNING: This page does not describe the selected car, but rather 32 other vehicles, including the 1990 Pontiac Trans Sport, 1990 Oldsmobile Silhouette, 1990 GMC Vandura Special, 1990 GMC Vandura, and 1990 GMC Value Van. However, it is still accessible from the selected car via links, so may be relevant.
On all light duty vehicles, check transmission fluid every 12 months or 7500 miles. On heavy duty vehicles, check fluid level every 12 months or 6000 miles. Periodic draining and refilling is not required.