In a 20 quart pot, sauté onions in olive oil for 15 minutes or until onions start to brown. Put garlic into pot and cook for 2 more minutes.
Place potatoes, kielbasa, salt, pepper, and thyme on top of the onions and pour in the white wine and fish stock. Cover with a lid and cook medium high heat for 20 minutes.
Place corn, clams, and lobster into pot for 5 minutes. Covering the pot tightly.
Add the shrimp and mussels to the pot for 5 minutes. Test the potatoes for tenderness. The lobster and shrimp should be opaque and the clams and mussels should be opened. If not, cook a few more minutes.
With a large slotted spoon, remove the vegetables and seafood to a large bowl.
Add 3 tablespoons of butter to the broth and bring to a boil. Season to taste. Serve over the clambake with crusty bread.