Can you mix regular and premium gas to save money? What to know as prices soar
Russia’s invasion of Ukraine has led to crippling gas prices across the U.S., spurring some drivers to search for cost-cutting measures at the pump.
For some, that might mean trading more expensive premium gas for regular unleaded.
Most experts agree drivers can fill up with a lower level of octane without disastrous consequences. Here’s what to know.
Can I put unleaded fuel in a car that takes premium?
According to Fuel Express, you can put regular gas in your car or truck even if the manufacturer recommends premium. But if they require premium, then pumping unleaded might cause issues.
“Just because premium is recommended doesn’t mean you have to use it; you can easily use regular gas without compromising the engine,” Fuel Express said.
Others may disagree.
Citing World Toyota’s Service Center, 11Alive reported drivers should not put regular gas in a vehicle that takes premium because the lower octane levels found in unleaded gas could create “knocking” that damages the vehicle’s motor. It may also void your warranty.
Octane ratings refer to the “87” or “89” you often see on regular and plus gas pumps. The higher the octane rating, the less likely a car will experience a “mistime combustion,” which creates the engine knock sound, according to The Drive. A higher-octane gas, such as premium, helps prevent engine knock.
In older cars that require premium, The Drive reported, fueling with 87 octane would almost immediately cause the engine to start knocking. But newer model cars are better equipped to handle it.
“If you mistakenly fill up with regular fuel, your car’s ECU will adjust engine timing and performance to work with the lower-octane fuel,” The Drive said. “In most cases, this is OK for the times when there are no premium pumps around, but it’s not ideal to run the cheapest fuel possible for extended periods of time.”
How do I know if unleaded gas will damage my car?
The key is to determine whether premium gas is required or merely recommended, according to the automotive experts at Edmunds.
“Advances in engine technology mean that even if the owner’s manual recommends premium gasoline, the car will typically run on regular without issue and won’t damage the engine in any way,” Edmunds reported. “The car’s performance might suffer only slightly: It might be a half-second slower from 0 to 60 mph, for instance. But the average driver isn’t likely to notice this drop-off.”
While putting regular gas in cars that called for premium was previously a sure-fire way to damage engine components, today’s engine control systems “effectively tune engines on the fly,” according to Edmunds.
That means drivers have “more flexibility in the grade of fuel that they can use safely,” the website reported.
Edmunds maintains lists of cars in which premium gas is recommended versus required. You can find them here and here.
Drivers can also look up what their manufacturer recommends on the government’s website at www.fueleconomy.gov.
What will happen to my vehicle if I use unleaded instead of premium gas?
Carmakers call for premium gas in vehicles that have shown they run at maximum efficiency on premium fuel, according to Jerry Reynolds, host of the show CarPro.
That means your car experiences maximum acceleration and top speeds using premium gas, Reynolds said in a blog post, and it will also get the best fuel economy. Switching to regular unleaded could lead to a loss of 10% fuel economy, but he said drivers will still save money buying unleaded given the difference in cost between regular and premium.
For drivers who typically use premium gas looking to make the switch, Reynolds recommends they fill up with a tank of premium and write down the starting mileage.
“Run the tank as near empty as you safely can, then fill up again with regular fuel and see what the fuel economy difference is and how your car performed,” he said. “If the drop in fuel economy is not substantial, and the car performs well, stay with the regular, you won’t hurt a thing.”
There are some cars, however, in which Reynolds does not recommend using regular unleaded gas.
They include those with high-performance engines, like a Porsche or Corvette, any vehicles hauling heavy loads, cars that are more than 10 years old and cars that have a supercharger.
Can I mix premium and unleaded gas?
Yes, drivers can mix the two types of fuel. The combined gas types will result in an octane level somewhere in the middle — something the vehicle “will survive,” according to The Drive.
“That said, if your vehicle requires premium fuel, it’s a good idea to top it off with the good stuff as soon as you’re able,” the website said. “If you’re really worried about the engine developing a knock, you can add just enough regular fuel to get you to the next station, but be sure you have enough fuel to reach the destination.”
This story was originally published March 16, 2022 at 10:50 AM with the headline "Can you mix regular and premium gas to save money? What to know as prices soar."
