Mechanics Explain What to Do If Someone Accidentally Fills a Diesel Tank With Gasoline
“A friend of mine bought his son a diesel car. His son called him asking, ‘Do I put regular or super unleaded in?’”
A Redditor shared that story in the Ask a Mechanic forum. As funny as it sounds, mechanics quickly piled on with serious advice. Filling a diesel vehicle with gasoline can destroy the fuel system. What you do next matters.
The consensus came down to three immediate steps:
- Don’t start the vehicle
- Call a tow truck
- Disconnect the battery, just to be safe
The most upvoted comment was blunt: “Don’t start the truck and drain the tank.”
Another mechanic explained what happens next if you ignore that advice. “DO NOT START IT, you will ruin the fuel system. Tank must be fully drained and rinsed with diesel.”
A third commenter added firsthand experience. “I did the same while on vacation in Ireland. Not fun, but at least I didn’t try to start it.”
How to keep a Good Samaritan from making it worse
Several commenters raised one nightmare scenario. “If you turn the key, gas will go to the fuel pump and ruin it.”
That creates a problem if a tow truck driver tries to start the vehicle to load it.
Mechanics offered multiple ways to prevent that from happening. “Open the hood, disconnect the batteries. This will prevent the fuel pumps from running.”
Another suggested a more technical solution. “You just pull the fuel pump relays or fuses.” The downside is knowing which ones to pull under pressure.
For most drivers, the simplest solution remains the safest one: Disconnect the battery and make it impossible to start. See the Reddit post embedded below:
Just put 14 gallons of 93 in my diesel on an empty tank, what do I do
byu/FALLOUT_BOY609 inAskAMechanic
