I've been running regular unleaded gas in my RV, but when it came to winterize, I'm not sure if the gas jockey followed my instructions to fill with premium. Is it safe to start the vehicle if it has been stored over the winter with regular unleaded gasoline treated with Sta-bil? The manual says to use high quality fuel, but does not indicate higher octane. My concern is phase separation causing potential engine damage. I don't know if I should start it and see what happens or have it towed to a dealer and have the tank drained. Any advice? Winter here is six months with a fair amount of sub-zero temperatures.

4 Answers 4


There’s no reason at all to concern yourself. Crank it up whenever you’re ready. Gasoline does lose some of its volatility over time. If you’re planning to park for an extended time, disconnect battery. Im a certified auto tech.

  • I am just concerned about phase separation and potential engine damage. We have been having a lot of subzero weather lately. Jan 24, 2019 at 20:47

The ads for Sta-bil say it's suitable for all fuel types, so I can't see it being a problem, assuming your engine is tuned for regular. I also assume you're only storing it for a few months, so fuel degradation shouldn't be too bad anyway.


Premium fuel is of no concern, it will neither help or hinder winter storage. ( Anyone says different they just like the sound of their voice) all it will do is empty you wallet faster due to the higher cost. That being said, the "Sta-bil" should have helped...altho it doesn't last forever either, it does a decent job keeping gasoline from turning to some foul smelling liquid that your engine won't run on (for very long). It should be just fine!


While this may not exactly answer the question, I'll give a tip: you could find if you can purchase small-engine 4-stroke gasoline somewhere. At least in Finland, it's widely available. It's very expensive, but lasts for a long amount of time in storage. It's mainly intended for rarely operated small engines, but in the 4-stroke fuel variant, I think there's nothing to prevent from using it in a car engine, RV engine, or whatever large engine you may have.

The only problems you have are:

  • It's sold in small containers (5 litres)
  • If your tank is already full, you have to drive it empty

Obligatory link.

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