Can 95 and 98 be mixed together?
3 Answers
95 and 98 cannot be mixed together. Mixing gasoline can affect the service life of the car's ignition system, fuel injectors, and spark plugs. Gasoline can be classified into different types based on its source: straight-run gasoline, catalytic cracked gasoline, thermal cracked gasoline, reformed gasoline, coking gasoline, alkylated gasoline, isomerized gasoline, aromatized gasoline, etherified gasoline, and polymerized gasoline. 98-octane gasoline is composed of 98% isooctane and 2% n-heptane, while 95-octane gasoline is composed of 95% isooctane and 5% n-heptane. The main difference between them lies in the purity of isooctane. The higher the purity of isooctane, the stronger the anti-knock property of the gasoline.
I've been driving for over 20 years, and mixing 95 and 98 gasoline occasionally doesn't cause major short-term issues. The engine won't suddenly explode because the octane rating will balance between the two, with some adjustment in anti-knock performance. The key point is that manufacturers recommend specific fuel grades during vehicle design - for instance, 98 may be suggested to optimize power or fuel efficiency. Long-term mixing may confuse the electronic control unit's learning pattern, potentially causing inaccurate ignition timing, increased fuel consumption, or minor knocking. If you accidentally use the wrong fuel in emergencies, don't panic - just consume it quickly and refill with the correct type. However, it's best to avoid this practice, especially for turbocharged or high-performance engines. Consulting the manual remains the most reliable approach.
I usually drive a regular commuter car and mix 95 and 98 octane fuel to save money, blending the cheaper 95 to balance costs. In the short term, driving feels normal with no warning lights or issues; but the mechanic mentioned that the engine automatically adjusts the air-fuel mixture based on the octane rating. Frequent mixing might confuse the ECU, leading to shaking or power loss. If mixed too often, it could end up costing more in repairs long-term. It's advised to minimize fuel mixing—using the recommended octane is safer and more reliable. For savings, consider alternatives like regular maintenance.
