Slide in under the engine and look up at the bottom of it. That will be the oil pan that you are looking at and it is bolted to the bottom of the engine.
It will be in the oil pan on the bottom
The oil pan must be removed.
Near the rear of the pan. It is there, you need to look more closely.
In the oil pan
Inside the oil pan.
it is on the right side of the oil pan...
It is on the oil pan on the far rear; you will need to raise the vehicle to get at it.
The oil pan is mounted on the bottom of the engine block.
Bottom of block.
Place a drip pan below the oil pan in your 1988 Chevrolet. Remove the oil pan plug. Allow the oil to drain out. Put the plug back into the bottom of the oil pan. Fill the motor with new oil.
It is in the back bottom of the oil pan. Just look around the bottom sides of the oil pan and you will see a bolt head. Take it out.
The oil pan is on the bottom.