Symptoms
- Car, boat, or equipment will sit unused for weeks
- Unsure whether stabilizer is needed for a specific situation
- Old gas already in the tank from a previous storage period
Likely causes
- CommonUncertainty about when stabilizer is actually neededStabilizer matters most for equipment sitting idle a month or longer, not for a car driven regularly.
- CommonEthanol-blended fuel breaking down fasterMost pump gas contains ethanol, which absorbs moisture and degrades faster than ethanol-free fuel.
- PossibleStabilizer added to already-old, degraded fuelStabilizer prevents future degradation but doesn't reverse damage already done to old fuel.
What to do
- Decide if you need it: daily-driven cars generally don't need stabilizer since the tank cycles through fuel regularly.
- For any vehicle or equipment (car, mower, generator, boat) sitting unused for a month or more, add stabilizer before storage.
- Fill the tank close to full first, since a fuller tank has less air space for condensation to form.
- Add the stabilizer according to the bottle's ratio for your tank size, then run the engine for several minutes so treated fuel circulates through the system.
- If gas has already sat for several months untreated, especially in small engines, consider draining and replacing it rather than relying on stabilizer alone.
- Label the date you added stabilizer if the item will sit for an extended, uncertain period.
Tools and parts
Fuel stabilizerSearch: “fuel stabilizer for small engines and cars”
When to call a pro
If an engine won't start after long storage even with stabilizer used correctly, a small engine shop or mechanic can check for gummed-up carburetor jets or fuel lines.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.