Fact check: Watered-down diesel can't be used in a gas-powered vehicle
The claim: You can put watered-down diesel in a gas vehicle tank
Drivers panicked about stations running out of gas after the ransomware attack on the Colonial Pipeline got a not-so-friendly tip from a widely shared social media post.
“Remember if the station is out of gas you can put diesel in your car as long as you water it down,” the May 11 Facebook post read.
The post was shared about 1,800 times and generated a few comments that pointed out the absurdity of putting a diesel-water mix in a gasoline engine. But others worried that an unsuspecting person might take it seriously.
“This is dangerous,” one commenter wrote. “People believe what they read on Facebook.”
In this case, they shouldn’t believe it – even if it was meant to be a joke. Diesel fuel is thicker than gasoline and can damage components in a gas-powered vehicle. Adding water doesn’t help, though, and can do its own harm.
The Facebook user who shared the post doubled down on the claim when contacted by USA TODAY, insisting water is a way to correct for diesel engines having more power.
But that's not at all how it works, as the AAA auto club noted.
“It’s definitely a bad idea,” said David Bennett, manager of repair systems for AAA. “Water and internal combustion engines do not mix. Not at all.”
Diesel or gas?
While both diesel and gas come from crude oil, diesel is thicker and not as combustible as gasoline, according to J.D. Power. Gasoline and diesel engines operate differently too, with gas engines relying on spark plugs for ignition of the fuel, compared with a compression system in diesel engines.
“In short, gasoline and diesel engines are designed to operate using only their specific fuel-type and not the other,” according to a post on the website of J.D. Power, an automotive analysis firm.
Bennett said gas pumps make it easier to avoid putting diesel in a gas-powered vehicle. The nozzle on a diesel pump is larger than the opening in a vehicle with a gasoline engine, he said.
Filling a gas-powered vehicle with either diesel or water will cause problems, Bennett said. Mixing the two won’t help.
Both will cause internal damage and costly repairs, he said.
Fact check: Yes, viral photo shows gas hoarding in Alabama after Colonial Pipeline hack
If pure diesel goes into a gas-powered car, it may run for a short time, but eventually it will stop, he said. Mechanics then will have to remove the fuel, drop the gas tank and clean or replace fuel lines, filters and injectors.
Water is not combustible and can damage internal parts of the engine if it makes its way into cylinders, he said.
None of the damage caused by putting water or the wrong fuel in the vehicle would be covered under the manufacturer’s warranty, either, Bennett said. Vehicle owners must use the fuel outlined in their owner's manuals.
Similarly, vehicle owners need to avoid putting gas with higher contents of ethanol – such as E85 – into vehicles that aren’t designed for it, he said. Vehicles that can handle those fuels have specially designed components that can stand up to the corrosive ethanol content.
Bennett said anyone who puts water or the wrong fuel in their vehicle should turn it off immediately and have it towed to a mechanic who can clear out the fuel and make sure it hasn’t damaged other parts of the vehicle.
Our rating: False
The claim that you can use watered-down diesel fuel in a gas-powered car is FALSE. An expert with the AAA auto club said putting water or diesel in a gas-powered vehicle will result in internal damage to the vehicle that would not be covered by a manufacturer’s warranty.
Our fact-check sources:
USA TODAY, May 13, Colonial Pipeline shutdown: Expect gas shortages to go away by Memorial Day, expert says
Car and Driver, accessed May 13, Diesel vs. Gasoline: Everything You Need to Know
NBC Connecticut, Sept. 16, 2019, Do You Know What's in Your Gas Tank?
The Atlanta Journal-Constitution, Oct. 18, 2018, Georgia drivers: What to do if your car is damaged by tainted gas
AAA auto club, accessed May 13, AAA official website
J.D. Power, Nov. 19, 2020, What Happens if you put Diesel in a Gasoline Car?
LinkedIn, accessed May 13, David Bennett, AAA manager of repair systems
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Our fact check work is supported in part by a grant from Facebook.
This article originally appeared on USA TODAY: Fact check: Watered-down diesel can damage a gas-powered car's engine
