What Happens if you Put the Wrong Gas in Your Vehicle?


Does your car require premium gas, and you filled it up with regular? Or vice versa? Did you accidentally put regular gasoline into a vehicle that requires diesel? The results of these mistakes vary depending on the situation but know this: it happens more often than you think, and you shouldn’t be embarrassed. The good news is that most vehicles today are smart enough to know the difference. They come equipped with electronic fuel management systems to notice gasoline mix-ups and adjust the ignition timing and fuel injection to compensate. How cool is that? Even with this advanced technology, it’s always best to use the kind of fuel your car’s manual requires. But mistakes happen.

When you pull up to the pump, pay attention to the octanes; at most gas stations, they are clearly labeled. Regular unleaded gasoline has an octane level of 87, premium is 91 or 93 and plus falls somewhere in the middle, usually around 89.

So, what happens if you make a mistake and put in the wrong octane?

Putting Regular Octane Gas into a Vehicle That Requires Premium

Best case scenario: you notice your engine isn’t performing as well as it should, and you see a drop in fuel economy. The regular fuel will burn off, and when it comes time to fill up again – switch back to premium. Worst case scenario: you start to hear a rattle or high-pitched noise, which means the fuel isn’t burning correctly and could indicate some damage. Pullover and call a mechanic.

It’s also important to know if your car requires premium fuel or simply recommends it. There is a difference, and vehicles that require premium fuel are less flexible when mistakes happen.

Diesel Fuel Vehicles

Diesel and unleaded fuels are very different and mixing them up can be costly. Although this mistake is less likely because the pumps are different colors and the nozzles are different shapes, it does happen.

If your vehicle requires diesel fuel and is accidentally filled up with unleaded, you hopefully realize the mistake before turning on the engine. Simply turning the key in the ignition can cause severe damage. Diesel fuel acts as a lubricant, and unleaded fuel strips it away. The wrong kind of gas in a diesel engine could damage the fuel pump, filter, and injectors. Call for a tow truck and take your car to a mechanic who can drain your tank and flush out your fuel lines.

If you mistakenly put diesel fuel in a vehicle that requires unleaded, your car may not even start. Simply put, gas engines can’t combust diesel fuel. This will likely require a tow and tank drain, too. That cost can range anywhere from $500 to the thousands.

Ensuring your car is filled with the correct kind of fuel is essential. If you’re a Protect My Car customer and realize you made a gasoline mix-up, call our Roadside Assistance number before you start driving. It’s cheaper and easier to siphon the gas out than it is fix a major problem after the fuel gets in your engine. Visit www.protectmycar.com for more information about our plans, pricing and the full suite of services available to you.

If you have further questions about your vehicle’s fuel requirements or want to understand octane better, check out the U.S. Energy Information Administration, they have an entire section on their website dedicated to understanding the basics of gasoline and octane.

About Protect My Car

Protect My Car is an extended auto warranty company. Our goal here at Protect My Car is to eliminate your worry of being financially responsible for an expensive mechanical breakdown. With our extended auto warranty, you don’t have to worry about being fully burdened with the cost of a covered repair.