Can You Mix 87 and 91 Gas? What Happens When You Do?

Is Mixing 87 and 91 Gas Safe?

Well, if you’ve ever wondered whether you can mix 87 and 91 gas, you’re not alone. It’s actually a question I’ve had myself, and a friend of mine recently asked me the same thing. Here’s the thing: while it’s not ideal, mixing the two types of fuel won’t likely cause major harm in the short term. But that doesn’t mean it’s the best choice for your vehicle. Let's dig into the details.

What’s the Difference Between 87 and 91 Gas?

Honestly, this is where things can get a little confusing if you don’t deal with fuel types often. The numbers 87 and 91 refer to the octane rating of the fuel, which is basically the fuel’s ability to resist knocking or pinging during combustion.

• 87 octane is the regular unleaded gasoline you’ll find at most gas stations. It’s perfectly fine for cars that don’t require higher performance fuel.

• 91 octane is considered premium gas, and it’s used for vehicles with higher-performance engines, such as sports cars or luxury vehicles. These engines have higher compression ratios, which means they need fuel that burns more evenly.

So, to put it simply: 87 is for most everyday cars, while 91 is for cars that demand a higher level of performance.

Can Mixing 87 and 91 Gas Damage Your Car?

Short-Term Effects

Honestly, if you mix 87 and 91 gas, it’s not likely to immediately damage your car. However, mixing these two fuels could result in an octane rating somewhere between 87 and 91, depending on the ratio. For example, if you mix half a tank of 87 with half a tank of 91, you’ll get an octane rating of about 89. This won’t really cause harm to most modern cars, but it’s not optimal for vehicles that need a higher octane for peak performance.

I remember a time when I was driving a friend's car, and we ran low on gas, but there was a mix of 87 and 91 octane left in the tank. The car ran fine, but I did notice a little hesitation when accelerating. It wasn't a huge issue, but I figured that the fuel wasn’t quite optimized for the engine.

Long-Term Consequences

Over time, if your car is meant to run on higher-octane fuel and you consistently mix in 87, you might notice some performance issues. In particular, cars with high-compression engines could suffer from things like knocking, poor fuel efficiency, and reduced engine performance. It's not something that would happen overnight, but if it becomes a habit, it can certainly take a toll on your car in the long run.

What Should You Do if You Accidentally Mix 87 and 91 Gas?

Don’t Panic, Just Drive Carefully

If you realize you’ve mixed 87 and 91 by mistake, don’t stress too much. Unless you’ve made a regular habit of it, your car will likely be just fine for the time being. You might notice some slight changes in how the engine performs, like a little more pinging or reduced acceleration, but nothing catastrophic.

That being said, if you’re using a car that requires premium fuel, it’s probably best to top it off with the correct fuel ASAP. Over time, if you keep using lower-octane fuel, you might begin to notice long-term issues.

Avoid Making It a Habit

This might sound like a “duh” statement, but it's really important: avoid mixing the two fuels regularly. If you’re putting in the wrong octane regularly, you could be doing unnecessary damage to your engine, and that’s going to hurt your wallet in the long run.

Conclusion: Is Mixing 87 and 91 Gas Really That Bad?

Well, the short answer is that mixing 87 and 91 gas won’t kill your car immediately, but it’s definitely not something you should make a habit of. It’s always best to stick with the fuel type recommended by your vehicle’s manufacturer for the best performance and longevity of your engine.

If you’ve done it once by mistake, don’t worry too much—but remember, consistency is key! You don’t want to create unnecessary wear and tear on your engine. If you’re ever unsure about what fuel your car needs, just check your manual or ask an expert. Your car will thank you!

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