* Cracked Fuel Line: A crack in the fuel line, particularly one running near the engine block or oil pan, could allow fuel to seep into the engine and eventually find its way to the oil pan. This is more likely if the line is old, brittle, or improperly routed.
* Faulty Fuel Pump: A leaking diaphragm in the fuel pump could allow fuel to leak past its seals and into the engine compartment. While it wouldn't directly go *into* the oil pan, it could pool near it and then find its way in through a crack or opening.
* Cracked Carburetor: A crack in the carburetor body or a faulty float bowl gasket could also lead to fuel leakage. If significant, it could again find its way into the oil pan.
* Damaged or Cracked Engine Block or Oil Pan: This is a serious issue. A crack in the engine block or oil pan itself, particularly around a freeze plug (core plug), can allow fuel (or other fluids) to enter the oil pan. This is often caused by overheating, severe impact, or corrosion.
* Failed Fuel Injector (if equipped with fuel injection, though less likely on a '68 Impala): While less common on a 1968 Impala (which likely has a carburetor), if it *does* have a later fuel injection system retrofitted, a faulty injector seal could allow fuel into the engine.
* Improperly Installed or Damaged Fuel Return Line: If there's a fuel return line that's not properly secured or damaged, it could leak fuel near the engine.
Why this is serious: Mixing gasoline with engine oil dramatically reduces the lubricating properties of the oil, leading to severe engine damage. It can also create a highly flammable situation. Do not run the engine if you suspect gas in the oil.
Troubleshooting steps:
1. Inspect the fuel lines and pump visually: Look for any signs of leaks, cracks, or rust.
2. Check the carburetor for leaks: Inspect the bowl, gaskets, and connections for any fuel seepage.
3. Check the oil: If it's noticeably thinner than usual, smells strongly of gasoline, or shows signs of discoloration, you almost certainly have fuel in the oil.
4. Carefully inspect the engine block and oil pan: Look for any cracks or damage, especially around freeze plugs.
It is strongly recommended to have a qualified mechanic diagnose and repair this issue. Running the engine with gas in the oil will likely cause catastrophic engine failure.
