I haven't used my car in a while. The last time I refueled was back in December. I've used it a couple of times but nothing very significant, so I have over 30% of a tank left.

Yesterday I drove it "hard" (kept it for a few minutes at 6K RPM, 120kph in third gear), and then drove around for 1 hour on the highway.

The gauge didn't even move. It's a 1.6L engine, car weighs barely 1000kg, so it's quite fuel efficient.

I did not notice anything strange while driving it. It didn't knock, didn't misfire, it was as "powerful" as I remember.

Should I be worried about this fuel?

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    Welcome to Motor Vehicle Maintenance & Repair! Commented Jun 27, 2022 at 14:33

1 Answer 1


Refuel to a full tank and call it a day. If you were going to see issues with the fuel, you would have already seen them. If the vehicle is going to sit for a while, the best thing you can do for it is keep a full tank. This gives less atmosphere for ethanol rich fuel to draw moisture from. If you know you're going to leave it sit for a while, put some fuel preservative in it, like Sta-Bil (no affiliation). It will keep the fuel in good standing for up to two years.

  • thank you. I didn't know this kind of product existed. I'll investigate!
    – hjf
    Commented Jun 27, 2022 at 14:53
  • In high humidity Florida, USA, fuel stabilizer allowed my 3 year idle generator to start on the third pull. Definitely recommend any brand of this product.
    – fred_dot_u
    Commented Jun 27, 2022 at 14:56
  • @fred_dot_u - I'd assume it actually works longer than the two years they put on the bottle, but those be the directions. I have no problems using it in my small engine equipment, either. My vehicles usually don't sit for a long period of time, so I don't worry too much about them, but if I did, I'd not worry about using it there, either. Commented Jun 27, 2022 at 16:10
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    @findwindow - I may be a bit over cautious, however, the water in the fuel system which ethanol laced fuel can attract, can cause all kinds of issues besides just poor running. It can rust fuel lines if they are steel. It can clog up filters and injectors. Just lots of down sides to it. Not something I'd like to deal with. Commented Jun 28, 2022 at 16:10
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    @findwindow - If it's going to sit around a lot, keep it topped off. I keep mine filled on a weekly basis. Commented Jun 28, 2022 at 17:15

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