Can I not use 95 octane after using 98 octane?
3 Answers
After using 98 octane gasoline in a car, you cannot switch to 95 octane gasoline. The effects of using 95 octane gasoline after 98 octane are: 1. It may affect the normal operation of the engine; 2. It can lead to increased car noise, reduced driving power, and engine damage. The differences between 98 octane and 95 octane gasoline are as follows: 1. Different octane values: 98 octane gasoline is a mixture of 98% isooctane and 2% n-heptane, while 95 octane gasoline is a mixture of 95% isooctane and 3% n-heptane. 2. Different gasoline grades: Different gasoline grades represent different fuel anti-knock properties. The higher the gasoline grade, the better the anti-knock performance.
As someone who frequently tinkers with cars, I find this issue quite common. Simply put, whether you can switch from 98 to 95 octane fuel depends on your car's required octane rating. Modern car engines have a compression ratio, and high-compression performance vehicles need 98-octane fuel to prevent knocking—that abnormal vibration which damages the engine internals. If your car manual recommends 95 or lower, switching from 98 to 95 is fine; but if it requires 98, forcibly using 95 may cause knocking and eventually ruin the engine over time. Occasionally mixing fuels is harmless—for example, adding 95 when there's 20% of 98 left in the tank has negligible impact. I suggest checking the manual or consulting a mechanic—don’t risk saving a few bucks at the expense of engine longevity. The key is consistency; avoid frequent fuel switching to prevent conflicts with the car's computer adaptation.
I have an old car that's been running for ten years, and I often switch oil grades to save money. After using 98, you can switch to 95, but be careful if the car is suitable. For example, my old Ford recommends 92 octane, and switching from 98 to 95 was completely fine. However, my neighbor's sports car requires 98 exclusively, and when he tried 95, the engine started buzzing loudly. He had to rush to the dealership to clean the fuel system to avoid major damage. The key is to check the vehicle manual: if it says 95 is acceptable, then switching to 95 is cheaper; if it requires 98, don’t try to save money by using 95, as it may cause knocking and damage the engine. Mixing fuel grades isn’t dangerous—having a little 98 left in the tank won’t hurt. The real danger comes from long-term use of the wrong fuel grade. I recommend using a scanning tool to check your car model to avoid confusion.
