If you’re reading this, you’re probably considering purchasing (or currently own) a Honda Motor Company vehicle with the L-series four-cylinder engine, specifically the 1.5 liter L15BA or L15BE turbocharged direct-injected variant. If you want to learn more about its propensity to experience fuel diluting engine oil, keep reading.
Affected variations of the L-series: L15BA VCT turbo (2016+ Honda Civic) L15BE VCT turbo (2017+ Honda CR-V) L15BE VTEC turbo (2018+ Honda Accord) What is the L-series Engine? The Honda L-series engine is a common inline four-cylinder engine in 1.2L, 1.3L, and 1.5L configurations powering several Honda vehicles in the United States and worldwide. It was first introduced in 2001 with the Honda Fit and is available in naturally aspirated and turbocharged variants, using multi-port or direct fuel injection. In this article, I specifically want to discuss turbocharged versions of the L-series, including the 1.5L L15BA (found in the 2016+ Honda Civic) and the L15BE (found in the 2017+ Honda CR-V and 2018+ Honda Accord). What is the issue? Like most automakers, Honda has experienced oil-fuel dilution issues with their engines over the years. The L-series engine is reasonably reliable, but the company has faced lawsuits with its turbocharged direct-injected 1.5L versions powering some of its most popular models, where fuel dilutes the engine oil. This isn’t a good thing because if the fuel ratio becomes too great compared to oil, the oil’s viscosity changes to where it can’t properly lubricate critical engine components, causing premature wear and ultimate failure. A great contributor to fuel diluting engine oil is the use of direct injection. When fuel dilutes engine oil, more fuel is injected than what is vaporized. The fuel injectors are located within the combustion chamber (rather than behind the intake valves used in port injection), so naturally, not all fuel will initially vaporize. This remaining fuel can adhere to the cylinder wall and is sucked past the cylinder’s piston and mixes with the crankcase oil. The probability of fuel diluting oil is even greater in colder climates and when short trips are frequent. When the engine can’t sustain operating temperature for very long, the chance of remaining fuel vapor burning off declines. Owners can quickly identify if this problem is occurring by checking the engine oil level. Over time, if the level increases beyond the full mark, fuel is diluting the oil. If the oil dipstick also has a strong gasoline smell, that’s a sign as well. Generally speaking, every engine will have a little bit of fuel dilution. But with modern engines today, automakers have ramped up fuel injection pressure and compression ratios, dramatically increasing the chance of this dilution occurring. In Honda’s case, owners have also reported a strong smell of gasoline inside the cabin. And with the addition of turbocharging, the chance of fuel diluting engine oil is even greater compared to an engine being naturally aspirated. With my 2019 Hyundai Tucson, I have experienced fuel diluting the engine oil, but not to the severity Honda owners are experiencing. This likely is due to my engine not being turbocharged. What should I do if I own or want to buy a vehicle that has this engine? When it comes to fuel dilution, not much can be done. In general, the engine design itself is the reason for dilution, so the only option owners have is to try and slow down the dilution rate and live with the problem. Honda supposedly has recalled 2016 through 2018 Civics and 2017 through 2018 model year CR-Vs for this issue, but strangely omitted 2018 Honda Accords, which use the same engine. Despite not including the Accord, I’ve read reports of fuel dilution occurring with that vehicle and even happening to 2020 model year 1.5s regardless of which car they’re installed in. As of now, it appears Honda has failed to remedy the problem effectively despite it being known for more than five years. The best advice I can give Accord, Civic, and CR-V owners is to change the oil frequently and use quality gasoline, possibly trying premium fuel for greater knock-resistance. Changing the engine oil will not necessarily prevent fuel dilution, but it is the best proactive measure to ensure the oil viscosity is appropriate for protection against wear. 3,000-mile engine oil has better protection than 5,000-mile oil because oil breaks down over time, so longer intervals offer less protection. This suggestion is geared to preventing damage that can be caused by dilution reducing the oil's viscosity too much. Use high-quality full-synthetic oil and change it at 3,000-mile intervals rather than Honda’s 7,500-mile recommendation. Honda’s very thin recommended oil weight (being 0W-20) is likely accelerating the dilution, so consider using thicker oil such as 5W-30 or 5W-40 to slow down the dilution, especially if you live in a hot climate. But be cautious with using oil that’s too thick, or vital passageways can become blocked and damage components, such as variable valve timing solenoids. Above all else, oil is cheap, and engines are not. Should I buy a vehicle with this engine? Compared to the dilution affecting my Hyundai Tucson, Honda’s is by far the most severe I’ve researched. Because of this, I strongly urge prospective buyers to stay away from it. If your heart is still set on a Civic, CR-V, or Accord, consider purchasing one with a trim level that doesn’t have the 1.5L, if possible. For example, with the Accord, a 2.0L turbocharged engine is optional over the 1.5L if you select a higher trim level. This 2.0L (K20C4) is from Honda’s K-series instead of the L-series and doesn’t appear to be as affected by fuel diluting the engine oil, though only time will tell. Opinion Fuel diluting engine oil is nothing new with today’s vehicles. I’ve begun to come across reports of Toyota and Mazda four cylinders also experiencing this. I’m confident this issue will eventually affect other automakers. So far, it appears four-cylinder engines are most susceptible to fuel diluting the engine oil, likely because of their higher compression ratios. I have yet to learn of a V6 or V8 experiencing this dilution, but I’m sure examples are out there. Interestingly, in a 2016 Honda Civic manual, page 494 explicitly states, “Under certain driving conditions, it is normal for the engine oil level to rise above the upper mark.” Of all the vehicles my family and I have owned (including but not limited to Hyundai, GM (Chevrolet and Oldsmobile), Toyota, Ford, and Porsche), I have never come across an automaker explicitly mentioning this in their manual. Slight oil burning was always mentioned in the manuals I’ve read but never fuel dilution. This undoubtedly suggests Honda has known about this issue for many years yet continued to sell the vehicles to the public with no intention of addressing the problem. Honda did finally acknowledge the problem existed when owners brought forth the class action lawsuit in 2018. As of now, I think it’s not a question of if fuel will begin to dilute the oil, but when. I theorize a couple of things are causing this. Perhaps the compression ratio is too great than what the piston rings and oil control rings can handle. Maybe if the compression were lower, this problem wouldn’t exist. For fuel to mix with engine oil, it is somehow getting past the piston rings. In the end, it’s a shame Honda has experienced so many issues with their cars over the years. Back in the early 1980s and ‘90s, my parents owned several Hondas and loved them because they were reliable. The last Honda they had was a 1996 Accord and was sold in 2016 with more than 214,000 trouble-free miles. Today, Honda’s reliability has declined sharply within the last decade, not just with their engines but also with transmission and electronic components. For these reasons, I probably will not be purchasing a Honda or Acura any time soon. Additional resources Honda 1.5L Oil Fuel Dilution Lawsuit Now you know the truth behind Honda’s L-series 1.5L turbocharged I-4 engine. I hope you have found this information informative and helpful. Still have questions or comments about this issue? I'd love to help. Feel free to leave them in the comments section below. And if you know of any tips that could help mitigate or prevent fuel diluting engine oil, I’d love to hear them.
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