The Truth About Running Your Car on Cooking Oil: Myth vs. Reality

by AutoExpert   |  3 April, 2024

Share :

We all dream of cheap fuel, right? Especially something renewable, maybe even stuff people just throw away. That's why the idea of running your car on leftover cooking oil sounds awesome. Some folks swear by it, grabbing buckets of used grease from restaurants.

But hold on a sec – it's not quite that simple. You can't just pour fryer oil into your tank and drive off. Straight vegetable oil will wreck your engine. There's a bit more to it than that.

Car on Cooking Oil

First, the Difference Between Veggie Oil and Biodiesel

A lot of people get these mixed up. Biodiesel is fuel made from stuff like soybeans, but there's a whole refining process involved. It's regulated, some diesel cars can use it without any changes... but that's a different topic.

We're talkin' about literally using the oil you get at the grocery store, or score for free from the diner down the street. It's a much more DIY, kinda under-the-radar thing. Technically, it might even be illegal in some places since you're dodging fuel taxes and stuff.

Car on Cooking Oil

Okay, So HOW Do You Do It?

First, you gotta have a diesel engine. Those regular gas engines with spark plugs? Not gonna cut it. The fuel system just isn't built for thick stuff like veggie oil, plus modern cars have sensors that would freak out.

Even with a diesel, you can't just use veggie oil straight. It's too goopy – your engine won't spray it properly, and you'll get nasty buildup. Couple solutions here:

  • Mix it: Cut the veggie oil with regular diesel. Helps with the clogginess, but not a perfect fix.
  • Two Tanks: This is more serious. One tank has diesel for starting up and shutting down (when things are cold especially). The other has your veggie oil, which you gotta heat up because it gets thick when it's cold.

But even that's not enough. If you really wanna run on veggie oil long-term, there's more:

  • Special Injectors: Gotta make sure that fuel is SUPER clean, otherwise... engine problems. Good filters are a must, especially if you're using restaurant grease.
  • Beefier Glow Plugs: Those help with cold starts.
  • Heating the Lines: Wrap 'em with engine coolant hoses – warmer veggie oil flows way better.

There are companies selling conversion kits, but those get pricey, and you still might need a mechanic to install them.

Car on Cooking Oil

So... Is It Worth the Hassle?

Honestly, probably not to save money. Converting your car costs a bunch, and veggie oil isn't THAT much cheaper than diesel. Getting it free from restaurants is nice, but if this thing catches on, guess what? That free oil won't be free anymore.

Some people do it for the environmental aspect or the DIY challenge. Those are legit reasons, but if you're just looking to save a buck, veggie oil isn't your miracle answer.

Top News

Recomended:

Car Limp Mode vs. EV Turtle Mode: Causes & 2026 EPA Updates - Photo
Others
Car Limp Mode vs. EV Turtle Mode: Causes & 2026 EPA Updates

Over the years, car companies figured out they needed to idiot-proof engines and transmissions. Limp mode is their answer. When something breaks, the car basically hobbles itself on purpose so things

AutoExpert
The Chevy Stovebolt Six: The 72-Year Legacy of the
Others
The Chevy Stovebolt Six: The 72-Year Legacy of the "Cast-Iron Wonder"

Nobody at Chevrolet actually named it the Stovebolt. When the inline six-cylinder showed up in 1929, gearheads took one look at those slotted bolts holding the pushrod covers and oil pan together and

AutoExpert
The Heavy Truth: Why Your 2026 Car Probably Has an Aluminum Hood - Photo
Others
The Heavy Truth: Why Your 2026 Car Probably Has an Aluminum Hood

Cars are getting heavier every year, and there's no sign of it stopping. The EPA has been tracking this since the early '80s, and new vehicles just keep adding more weight. Electric batteries,

AutoExpert
Michelin vs. Uniroyal: The Tire Satisfaction Report Is Out - Photo
Others
Michelin vs. Uniroyal: The Tire Satisfaction Report Is Out

Buying tires is one of those boring grown-up chores that nobody enjoys. It costs a lot, it feels confusing, and once they’re on the car, most people are just hoping they did not make a bad cho

AutoExpert
Toyota Tundra vs. The World: Which Truck Reaches 250,000 Miles? - Photo
Others
Toyota Tundra vs. The World: Which Truck Reaches 250,000 Miles?

People love to argue Ford vs. Chevy when it comes to trucks. But if the question is “which one is most likely to still be running at 250,000 miles,” the answer is… Toyota Tundra.

AutoExpert
100-Car Michigan Pileup: How to Survive a Winter Highway Nightmare - Photo
Tips & Tricks
100-Car Michigan Pileup: How to Survive a Winter Highway Nightmare

Over 100 cars just smashed into each other in Michigan. Don't let this be you.Winter driving already sucks enough without worrying about getting caught in one of those insane multi-car pileups

AutoExpert
Stop Driving Like It’s 1995: 5 Habits You Need to Quit in 2026 - Photo
Tips & Tricks
Stop Driving Like It’s 1995: 5 Habits You Need to Quit in 2026

Modern cars have changed. Your driving habits should too.Cars today are nothing like the ones people learned to drive on 20 or 30 years ago. They've got sensors everywhere, computers handling

AutoExpert
The Physics of the Flip: What Does That Tab on Your Rearview Mirror Do - Photo
Video
The Physics of the Flip: What Does That Tab on Your Rearview Mirror Do

It's not decoration; it's saving you from getting blinded at night.Most people have driven past that little tab on their rearview mirror a thousand times without really thinking about what

AutoExpert
Green is the New Gray: The Global Car Color Report Is Out - Photo
Others
Green is the New Gray: The Global Car Color Report Is Out

The car color situation is still depressing, but there's a tiny glimmer of hope.Car colors have been boring as hell for years now. Everyone just buys white, black, or gray like we're livin

AutoExpert
90 Years of the Chevy Suburban: History, Hollywood, and Specs - Photo
Others
90 Years of the Chevy Suburban: History, Hollywood, and Specs

Seriously, what's it going to take to kill this thing? The Suburban hit 90 this year. That's insane. Your great-grandparents could've bought one new. And here we are in 2026 and Chevy

AutoExpert