Understanding the Honda CRV Oil Dilution Issue

Honda CRV Oil Dilution Explained: What You Need to Know

In recent years, the Honda CR-V and Civic have been plagued by an issue known as oil dilution, which has raised concerns among owners and automotive experts alike. This article delves into the causes, effects, and potential solutions to the Honda CR-V oil dilution problem.

What is Oil Dilution?

Oil dilution occurs when unburned fuel washes oil off the cylinder walls and is forced down into the crankcase, effectively adding fuel to the crankcase oil. In the case of 2016 through 2018 Honda CR-V and Civics, this issue has been particularly prevalent in models equipped with the 1.5-liter turbocharged engine, which is part of Honda’s Earth Dreams Technology lineup. The problem has been reported across various model years, primarily affecting vehicles in colder climates.

What causes Honda CRV Oil Dilution

A complicated series of unanticipated events cause the oil dilution. When Honda switched to direct injection fuel delivery and turbocharging, they created the problem. The direct injectors shoot high-pressure gasoline mist into the cylinder during the compression stroke. The fuel stream can reach up to 2,000 psi during the compression stork. The advantage of direction injection is that by injecting during the compression stroke, the fuel can vaporize better and faster because the heat of compression assists it. (Physics lesson: Any gas heats up as it’s compressed. It’s called the Ideal Gas Law of Physics. Read more here) The higher heat plus the high pressure do a much better job of vaporizing the fuel, and that helps combustion.

Unfortunately, in the engines affected by the oil dilution issue, Honda engineers aimed the high-pressure injectors directly at the cylinder wall opposite the injector. When the engine is cold, the fuel sticks to the opposite cylinder wall rather than vaporize. During the power stroke, the extremely high combustion pressure forces the raw gas past the piston ring gap and into the crankcase. Raw fuel enters the crankcase on many engines, and it’s usually vaporized as the engine heats up and the crankcase vapors are circulated into the intake manifold by the positive crankcase ventilation system (PCV). But during winter, the ECM adds more fuel than the engine can burn through the PCV system.

So the raw gas accumulates in the oil pan, raising the oil level.

Does the Honda Civic oil dilution and Honda CRV oil dilution problem cause engine damage?

It can. Overfilling any engine crankcase causes the crankshaft to whip air into the oil, causing foam. Foam doesn’t cool well and is easily compressible, so it affects the oil’s ability to remove heat, build pressure, and lubricate.

In this case, once the oil level rises to a certain point, owners may notice a whirling noise coming from the engine compartment. That’s the sound of the crankshaft whipping up oil/gas foam.

Worse yet, raw gas not only doesn’t lubricate, but it washes lubrication off critical metal parts.

What you can do about it?

The Honda CRV oil dilution problem is worse in cold weather and where the driver takes mainly short trips. The short trips prevent the engine from heating the oil enough to evaporate the excess fuel. You can help reduce the oil dilution problem by getting your Honda out on the highway for a 20-30 minute drive once every 10 days to drive off the excess fuel.

What is Honda doing about the oil dilution problem?

The eventual fix will involve an engine redesign. In the meantime, Honda is installing new software that adjusts the pressure and timing of fuel injection on a cold engine. As of August 2019, Honda has tested the software in 190,000 Honda CRVs and 89,000 Honda Civics.

In addition, Honda has issued a warranty extension for those vehicles. The extended warranty adds another year to the powertrain warranty, bringing it to six years. Plus, Honda has eliminated the mileage limits during this warranty period.

Where is the oil dilution problem happening?

Honda has identified 21 states that experience cold weather that accelerates the oil dilution problem. The Honda Civic and Honda CRV oil dilution problems affect as many as one million vehicles.

States affected by the Honda Civic oil dilution problem and the Honda CRV oil dilution problem

Maine, Minnesota, North Dakota, South Dakota, Wisconsin, Arkansas,
Connecticut, Illinois, Indiana, Iowa, Massachusetts, Missouri, Montana,
Nebraska, New Hampshire, New Jersey, New York, Ohio, Pennsylvania, Rhode Island and Vermont

©, 2019 Rick Muscoplat