Since i bought my car, i refueled twice so far. The first time I refueled was at a full service local Shell, which is always 20 or 30 cents more than anywhere else. People seem to rarely go there for gas because of the price (I drove by there often, and only saw like twice there were people buying gas there). I bought medium grade gas there (octane 91). After I went home, I immediately noticed the engine sound is different. It is now a louder sound and slightly more vibration, kind of like the engine not running smoothly. Before this tank, it was a less loud, lower frequency, more constant sound, but with minimal but noticible vibration (with the tank from the dealer when i bought the car). The second time I went to another more popular self-service Shell. This time I got the regular (octane 87). The engine now sounds back like the tank I got from the dealer when i bought the car. How does your Prius' ICE sounds like? Stale gas from the first Shell? Any possible damage to the engine? Thanks.
Unlikely that there'd be any damage. Modern engines adjust their timing to compensate for predetonation. I haven't noticed any changes, tank to tank, but we generally get our gasoline from similar sources.
Did not sound knocking to me (I watched some engine knocking videos in Youtube). It sounded more like other non-hybrid car I heard. Just louder than before and sounds not running that smoothly.
every brand of gas is a bit different and will make different sounds. not to worry. by the sound you prefer, i get the quiet stuff.
This is a fairly common occurrence, when you fill up at a station that doesn't have much traffic. Selecting a grade that doesn't get much use just makes the odds greater that you will get stale or contaminated fuel. Stick with regular at a high volume station and you will be fine. For those who are stuck on "premium" despite all the evidence to the contrary, buy your gas near the Country Club where you see a lot of BMWs.
