Fluid Check
Either too high or too low an oil level can cause slippage in all ranges or excessive noise.Fluid level should be checked with the selector level in Park position, engine operating at idle and vehicle on a level surface. Transmission oil should reach Full mark when at operating temperature (195°F). If level is checked cold (70°F), oil level should be 1/4" below Full mark to allow for fluid expansion.
Fluid should be checked every 6,000 miles with engine idling, selector lever in neutral position, parking brake set and transmission at operating temperature. Use only General Motors Dexron transmission fluid when adding oil. Do not overfill.