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2019 Toyota Prius Prime - Stale Gas a Problem?

I have a Prius Prime that can run for 25 miles or so on the battery but also has a gas engine. Best of both worlds! If I charge overnite at home and again at work I can make it both ways without using any gas. I’ve only been putting in a few gallons every 2 months.

My question is if not running the gas engine for extended periods is bad for it?

Check your owners manual. I bet your car keeps track of how often you fill up, and will run the gas engine as needed to use up enough gas to not be stale.

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One, if its going to be a while between fill ups (one month or more) use 93 octane fuel, it stores better. If its a couple months between fillups use Sta-Bil (following instructions on bottle for correct number of ounces/gallon).

Well, guess I was half right. From pg. 102 of your owners manual:

“■Notice about fuel
●For plug-in hybrid vehicles, fuel may remain in the tank for a long time and undergo changes in quality depending on the how the vehicle is used. Refuel at least 5.3 gal. (20 L, 4.4 of fuel every 12 months (refuel
a total of at least 5.3 gal. [20 L, 4.4] over a 12-month period), as this may affect components of the fuel system or the gasoline engine.
●If the vehicle has not been refueled for a certain amount of time and it is possible that the quality of the fuel remaining in the tank has changed, “No new fuel has been added recently. Please refuel” is displayed on the multiinformation display when the power switch is turned to ON mode. If the
message is displayed, refuel the vehicle immediately.”

So I’d be using Stabil, unless I was running through at least a tank every 6 months.

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That’s false.

Higher octane gas doesn’t store longer.

Regular and high octane gas both contain the same amount of ethanol.


And the ethanol is the determining factor on how long gas will last.


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I don’t think you will have a problem with the 2 month intervals. I have seen Ethanol gas go horribly bad around here in 4 to 6 months.

When the Volt first came out one of GM’s lines when asked about why it required premium fuel was because it lasted longer in storage, or so Car and Driver stated back at the time (2005?). However, I can find no evidence to support that now when looking for it.

And another question that could have been answered just by looking in the owners manual .

At some stations the premium option will be ethanol free (at least in my state). But you have to check each time you fill because it varies per station, and sometimes per pump at a given station. In some areas it’s also technically illegal to use the ethanol free stuff in anything but a race car, off-road toys, or small engine equipment - not that anyone ever checks.

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