Frequently Asked Questions

Why is Fuel Mixing with Engine Oil in the Crankcase?

If you notice gas mixed in with your engine oil, you should follow these instructions to address a potential fuel leak in your lawn mower, snow blower or outdoor power equipment.

What causes fuel to leak into my engine oil?

  • The fuel shut-off valve isn’t closed properly.
  • Fuel float in the carburetor being stuck in the open position due to gumming (caused by stale fuel) or debris.
  • How do I fix fuel leaking into my engine oil?

    • If your engine has a fuel shut-off valve, ensure that this valve is closed when the engine is not in use to prevent fuel leaks.
    • If carburetor problems are causing fuel to mix with your oil in the crankcase, you should perform a throughout cleaning. Find out how to clean your small engine carburetor.

    For any other specific questions or concerns related to fuel and oil, make sure to contact a Briggs & Stratton Dealer near you. You can also find carburetor cleaner, lawn mower oil and more service materials in our online store.

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