How Often McDonald's Really Changes Its Fry Oil, According To Employees

McDonald's french fries are the gold standard of what a fry should be. They're crispy on the outside with a fluffy center, golden brown, totally salty, and deep-fried in a specific vegetable oil blend of canola, corn, and soybean oils. Sure, the oil used for McDonald's fries has changed over the years, but that hasn't stopped the fast food restaurant from selling more than 255 billion individual fries in the United States every year. With all those fries going through the fryer, it makes one wonder: How often does McDonald's change the oil that's zapping all those sliced spuds into crispy, golden perfection?

According to employees who have detailed their stores' cleaning schedules online, the fryers usually get a fresh batch of oil every one to two weeks, with the timetable varying by store. Many employees on Reddit shared that their stores change the cooking oil once a week to maintain high food quality.

Cooking oil is one of the highest costs of running a McDonald's, and managing it is a major key to a franchisee's success. The amount of oil each location goes through varies, but data from an oil recycling project in the Netherlands shows the country's 263 stores went through 1,000 tons in 2021 (that's roughly 287,000 gallons). That comes out to about 1,000 gallons of cooking oil per McDonald's location that year; that's a lot of oil to manage. Throughout the day, McDonald's employees skim crumbs out of the cooking oil to keep it as clean as possible, and the machines also run the oil through periodic filtration. Luckily, fryers in McDonald's are largely automated to control temperature, which helps preserve oil.

McDonald's locations have a dedicated fryer for the chain's best-selling menu item. The World Famous Fries are not cooked in the same oil that finishes the chain's famous Chicken McNuggets or McDonald's ever-iconic Filet-O-Fish sandwich. The separation helps preserve the flavor and longevity of the cooking oil that touches your fries, and when it comes time to swap out that oil, there's a cool gadget employees get to use.

A TikTok video detailed the whole process, starting with an oil caddy wheeling its way to the fryers in the back of the restaurant. Employees simply empty the old oil through a drain at the bottom of the fryer system into the oil caddy for transport outside to a disposable unit. Fryers are cleaned and dried, and then refilled with new oil. 

Some McDonald's establishments (particularly in the U.K. and the Netherlands) recycle the dirty oil, transforming it into biodiesel to fuel vehicles like delivery trucks. The practice is ongoing in America, as well, including at the Dallas Fort Worth International Airport, where recycled cooking oil is turned into biodiesel and jet fuel.