A Toyota 4Runner owner with 340,000 miles on the odometer recently used an old-school mechanic trick by pouring a gallon of diesel fuel into his engine oil to clean heavy internal buildup. According to TikTok creator HP Medina (@_hpmedina_), whose video reached over 198,800 views, the engine’s internal components had grown crusty with age despite regular oil changes every 5,000 miles.
Why Mechanics Use Diesel Fuel to Clean Engine Sludge
Medina stated in his video that commercially available oil cleaning solutions weren’t strong enough for the severe buildup inside his high-mileage crankcase. According to Medina, diesel fuel contains heavy detergents that theoretically break down grime when the vehicle is driven briefly before an oil change. After pouring an entire gallon into the oil filler neck while stopped at a QuikTrip gas station, Medina drove the vehicle around before putting the 4Runner on a lift to drain the dark mixture. Upon removing the oil cap afterward, Medina noted that much of the crust around the internal baffle had disappeared.
Pro Tip: Viewers in the comment section debated the diesel method, with many suggesting alternatives like Sea Foam Motor Treatment or automatic transmission fluid (ATF) mixed half-and-half with motor oil to safely dissolve varnish and sludge without risking excessive thinning.
How to Keep a Car Running Past 300,000 Miles
Reaching the 300,000-mile milestone requires rigorous attention to routine vehicle maintenance rather than relying solely on quick fixes. According to financial platform MoneyLion, the three foundational pillars of high-mileage vehicle survival are oil changes, cabin air filter replacements, and transmission service. Engine oil acts as a vehicle’s lifeblood by clearing out wear-causing contaminants, with AAA recommending oil changes every 5,000 to 7,500 miles. Furthermore, Advanced Transmission Center notes that manufacturers typically suggest changing transmission fluid between 60,000 and 100,000 miles to preserve gear longevity.
Did You Know? Outlets like Motor1 have documented various modern vehicles passing the 300,000-mile barrier, including a 2010 supercharged Corvette and a Tesla Model 3, proving that longevity is achievable across different powertrain types through dedicated upkeep.
Frequently Asked Questions
Is putting diesel fuel in engine oil safe?
While some traditional mechanics use diesel fuel for its detergent properties to clean heavy sludge, it drastically thins the oil. Modern mechanics often recommend safer alternatives like Sea Foam or automatic transmission fluid (ATF).
How often should you change your engine oil?
According to AAA, drivers should change their engine oil every 5,000 to 7,500 miles to keep internal components properly lubricated and free of contaminants.
When should you change transmission fluid?
Advanced Transmission Center reports that vehicle manufacturers generally suggest changing transmission fluid between 60,000 and 100,000 miles.
What are your thoughts on using diesel fuel to clean engine sludge? Let us know in the comments below, and subscribe to our newsletter for more high-mileage maintenance tips and automotive guides.