Preheat the grill for medium heat.
Cut the squash horizontally into 1/4 inch to 1/2 inch thick slices so that you have nice long strips that won't fall through the grill.
Mix the oil with garlic and season with salt and pepper.
In a large bowl toss the summer squash with the olive oil. You can also brush the oil onto the squash.
Grill squash slices for 5 to 10 minutes per side, until they reach the desired tenderness. Brush with additional garlic oil, and turn occasionally to prevent sticking or burning.