We’ve all heard about older diesel engines being able to run on used cooking oil (please look it up before you destroy your newer engine, with its high-pressure injection system). But what if things go the other way around and somebody uses diesel fuel instead of engine oil for lubrication? A YouTuber has attempted this so you don’t have to, with a Ford Crown Victoria becoming the unlucky test subject.
The Ford Modular 4.6L naturally aspirated V8 that powers the second-gen Crown Vic is generally regarded as a reliable engine, with properly serviced units going past the 200,000-mile barrier. After all, this has gone down in history as the dominant Police Interceptor of the modern era—then there’s this rendering of a pickup truck version.
And while it may not seem like it, the goal here was not to kill the motor, at least not straight away. Instead, YouTuber Cleetus McFarland (his real name is Garrett Mitchell) wanted to see how far he could drive the vehicle in such conditions.
Diesel vs gasoline as an engine lubricant
However, due to an earlier test of the sort that saw him pouring gasoline into the engine crankcase resulting in an explosion (we’ll get back to this below), the stunt couldn’t be pulled out on the road.
As faith would have it, Cleetus acquired Florida’s Bradenton Speedway back in 2020 and has been using this as his automotive playground ever since—have you seen the mini Plymouth Duster burnout car serving YouTuber Roman Atwood at the location?
So, after removing the oil from the V8, Cleetus added some diesel and set off in his engine-torturing adventure. Now, if you wish to steer clear of spoilers, make sure to jump past the next paragraph.
The results of the test
If curiosity prevails, though, we’ll tell you that the enthusiast did 36 laps of the track’s 3/8-mile banked oval. That would be 13.5 miles of somewhat spirited driving, with an average of about 70 mph. And the fluid expelled by the V8 once the vehicle comes to a halt is coolant/water. Still, an engine teardown would’ve provided some interesting details of the damage caused by such antics.
And since this is an experiment, we can compare the said number to the 17 laps (6.3 miles) done by the vehicle relying on gasoline for lubrication. For the record, once the enthusiast removed the PCV (positive crankcase ventilation) lines that brought hot gases to the mix, the fiery issue mentioned above was overcome.
The chemistry behind it
In the video, Cleetus leaves a bit of a science void for people in the comments section to fill. And the audience didn’t disappoint, aptly pointing out that gasoline, diesel, kerosene, oils, and grease are all made up of carbon and hydrogen. However, the size of the molecules is different—a greater number of carbon atoms means bigger molecules, which results in less volatility, greater thickness, and extra lubricating properties.
Then again, some people prefer the empirical method, namely performing lubricity tests and observing the effects. And there’s no doubt about diesel being far less effective than engine oil, so, if this was ever a myth, you should consider it busted.