* Engine Variations: The 366 6.0L engine may have had different oil capacities depending on the specific configuration of the engine (e.g., type of oil filter, oil pan, etc.).
* Year Variability: Even within the same engine, oil capacity might have slightly varied between different production years of the 1990 model year.
How to Find the Oil Capacity:
1. Consult Your Owner's Manual: This is the most reliable source of information. Look for the section on engine fluids or maintenance.
2. Check the Oil Filler Cap: The oil filler cap on the engine is often marked with the oil capacity.
3. Contact a GMC Dealership or Mechanic: A GMC dealership or a qualified mechanic can provide you with the specific information for your model year and engine configuration.
4. Online Resources: Search for your vehicle's specific model and engine on reputable automotive websites or forums.
Important Note: Always use the correct type and quantity of oil recommended by the manufacturer. Overfilling the engine with oil can cause damage.
