Some 2019 Honda Passport owners notice a gasoline smell when checking their oil or observe the oil level rising above the full mark on the dipstick. This indicates oil dilution—fuel mixing with engine oil—a condition that has affected some Honda direct-injection engines.
What Causes Oil Dilution
The 2019 Passport's 3.5L V6 uses direct fuel injection, spraying fuel directly into the combustion chamber at high pressure. During cold starts and warm-up, some fuel inevitably washes past the piston rings into the crankcase. In a properly functioning engine, this fuel evaporates as the oil heats up and is removed through the PCV system.
However, short trips that don't allow the engine to reach full operating temperature prevent this fuel from evaporating. The fuel accumulates in the oil, diluting it. Over time, the oil level rises and you may smell gasoline.
Is Oil Dilution Harmful?
Mild oil dilution that resolves with occasional longer drives is generally not harmful. The engine is designed with some tolerance for fuel dilution. However, severe dilution significantly reduces oil's lubricating properties, potentially accelerating engine wear.
Oil diluted with fuel has lower viscosity (it's thinner) and reduced ability to protect bearings and other components. If the oil level rises significantly above the full mark, it can cause other issues including increased oil consumption as thin oil passes by piston rings more easily.
Driving Patterns and Climate
Oil dilution is most common in cold climates with drivers who take many short trips. The engine never warms up enough to evaporate the accumulated fuel. Drivers who regularly take highway trips or allow the engine to fully warm up before shutting off rarely experience problematic dilution.
If your driving consists primarily of short trips in cold weather, occasional longer drives help "cook off" accumulated fuel. Even a 30-minute highway drive once weekly can prevent excessive dilution.
Addressing Oil Dilution
If you detect fuel smell in your oil, check the level and note how far above full it reads. A slight overfill may not be concerning. If significantly overfull, have the oil changed and monitor the level. Shortening oil change intervals (every 5,000 miles instead of 7,500) during winter helps minimize dilution effects.
Honda released software updates for some direct-injection models that adjust warm-up fueling to reduce dilution. Consult your dealer about whether updates apply to your 2019 Passport.