Generator Fuel Stabilizer: Do You Need It?
Last updated:
Fact-checked by James Witkowski, ASE Certified Technician, 12 years small engine and generator repair.
Key Takeaways
- Add fuel stabilizer if you store gasoline in your generator for more than 30 days — it extends fuel life from 3-6 months to 6-12 months.
- Add stabilizer to a full tank and run the engine for 5 minutes to circulate it through the carburetor.
- Propane stores indefinitely and does not require stabilizer — a major advantage of dual-fuel generators.
- Without stabilizer, gasoline forms varnish deposits that clog the carburetor and cost $50-$150 to clean.
- For storage longer than 12 months, drain the fuel completely instead of using stabilizer.
Do you need fuel stabilizer?
Yes, if you store gasoline in your generator for more than 30 days. Gasoline degrades in 3 to 6 months,
forming varnish deposits that clog the carburetor. Fuel stabilizer (like Sta-Bil or Sea Foam) extends
gasoline life to 6 to 12 months. For storage longer than 12 months, drain the fuel completely and run
the carburetor dry.
How to use fuel stabilizer in a generator
To use fuel stabilizer: add the manufacturer's recommended amount (typically 1 oz per 2.5 gallons for
Sta-Bil) to a full tank of fresh gasoline, then run the engine for 5 minutes to circulate the stabilizer
through the carburetor and fuel lines. This ensures all fuel passages are protected. For dual-fuel
generators, only the gasoline side needs stabilizer — propane stores indefinitely.
Frequently Asked Questions
Do I need fuel stabilizer for my generator?
Yes, if you store gasoline in your generator for more than 30 days. Gasoline degrades in 3 to 6 months, forming varnish deposits that clog the carburetor. Fuel stabilizer (like Sta-Bil or Sea Foam) extends gasoline life to 6 to 12 months. For storage longer than 12 months, drain the fuel completely.
How much fuel stabilizer should I add to my generator?
Follow the manufacturer's recommended ratio — typically 1 ounce of stabilizer per 2.5 gallons of gasoline (Sta-Bil) or 1 ounce per 1 gallon (Sea Foam). Add stabilizer to a full tank, then run the engine for 5 minutes to circulate it through the carburetor. This ensures the stabilizer reaches all fuel passages.
How long does fuel stabilizer last in a generator?
Fuel stabilizer extends gasoline life to 6 to 12 months. After 12 months, even stabilized gasoline begins to degrade and should be replaced. For storage longer than 12 months, drain the fuel completely and run the carburetor dry instead of using stabilizer.
Can I use fuel stabilizer in a dual-fuel generator?
Yes, fuel stabilizer is only needed for the gasoline side of a dual-fuel generator. Propane stores indefinitely and does not require stabilizer. Add stabilizer to the gasoline tank, run the engine on gasoline for 5 minutes to circulate it, then switch to propane for storage operation if desired.
What is the best fuel stabilizer for generators?
The most popular fuel stabilizers for generators are Sta-Bil (red bottle for storage, blue for marine), Sea Foam (also cleans the fuel system), and PRI-G. All work by preventing oxidation and varnish formation. Sea Foam has the added benefit of cleaning existing deposits in the carburetor and fuel lines.
What happens if I do not use fuel stabilizer?
Without fuel stabilizer, gasoline in your generator degrades in 3 to 6 months. The lighter components evaporate, leaving behind varnish and gum deposits that clog the carburetor jets, causing hard starting, rough running, or complete failure. A carburetor cleaning or replacement ($50–$150) is typically needed to fix the problem.