Ah, time for another Achilles Heel, where we detail the little problems that can bring entire cars down. I’ve usually used this as an opportunity to bag on hideously complex German luxury cars, so let’s do something different for a change. As you probably know, Achilles Heels don’t just exist on vehicles that depreciate like office real estate during the COVID-19 pandemic, they can be found on all vehicles from all walks of life. Take Honda, a Japanese byword for reliability.
In the mid-2010s (that feels weird to write), Honda started the roll-out of its 1.5-liter turbocharged four-cylinder engine as a downsized successor for engines like the 2.4-liter K24 inline-four. On paper, it seemed dandy, with solid output and excellent low-end torque for running around town. Given its fitment in the popular Civic, Accord, and CR-V, this little engine was soon everywhere, and that’s where the problems started.
Unfortunately, the 1.5T has a habit of oil dilution when used for the sorts of short errands you’d expect to run in a Civic or CR-V. What is oil dilution? Well, it’s when unburned fuel makes its way past the piston rings and ends up in the crankcase, mixing with the engine oil and leading to some not-so-fun results. You see, gasoline doesn’t make for an amazing lubricant.
The biggest issue is that fuel mixed with oil lowers the viscosity of the oil, and oil needs viscosity to lubricate things properly. If it’s too watery, the correct film won’t build on critical components like bearings, thus accelerating engine wear. Oil dilution may cause misfires, noxious aromas, and emissions-related error codes. Fun stuff! In simple terms: Could engine go bam? Yes, engine could go bam.
In addition to short trips, cold climates can add to oil dilution woes thanks to condensation of vaporized fuel/air mixture. Just like how when you have a cold can of soda on a hot day, water vapor condenses into droplets on the cold can, a fuel-air vapor will condense into droplets on cold metal in the combustion chamber. German lubricant company Addinol explains:
Petrol settles on the cylinder walls during cold starts and is introduced into the oil via the piston ring. This results in a mixing of oil and fuel. Since the oil in the engine does not heat up strongly enough, the fuel is not completely burned. Parts of the fuel remain in the lubricant and continue to dilute it.
Cold start enrichment may also play a role in promoting oil dilution, as it’s typical for modern engines to run a little on the rich side following a cold start for a variety of reasons. Since some fuel settles on the cylinder walls when an engine is cold, enriching the air-fuel mixture can combat atomization losses to pooling. In addition, a richer mixture during engine warmup can help light off the primary catalytic converters, helping to lower emissions. The colder it is outside, the longer it will take for an engine to warm up. Granted, these tuning tricks are employed in pretty much every modern fuel-injected engine, so oil dilution in these Hondas is likely exacerbated by piston ring gap and/or some other issue in the engine’s design design.
If this rings a bell, that’s probably because this oil dilution issue has been talked about here and there for the past few years. In fact, Honda knew about the oil dilution issue back in 2018, when it issued a technical service bulletin in certain cold weather states to combat the oil dilution issue with “ECU and TCU software updates and replacement of the A/C control unit.” In addition, Honda issued a limited warranty extension on 2016 to 2018 Civic models with the 1.5T in 2019.
To increase customer confidence, American Honda is extending the powertrain warranty on the camshafts, rocker arm assemblies, and spark plugs from the original 5 years or 60,000 miles to 6 years with unlimited mileage from the original sale date.
So, did this round of fixes work? Allegedly not. A recent class action lawsuit, Wolf et. al. v. American Honda Motor Co., Inc., claims that oil dilution is still an issue on newer Honda 1.5T vehicles, including some notorious alleged issues with a 2021 CR-V. As per the class action complaint:
On or about February 17, 2022, Ms. Phelps’ vehicle went into “limp mode” while she was driving to work and began emitting smoke. “Limp mode” occurs when a car’s electronic control unit senses something drastically wrong with the transmission or engine. She had her vehicle towed to Hosmer Honda in Mason City, Iowa, an authorized Honda dealership, where technicians found fuel in the vehicle oil. Technicians inspected the vehicle for the source of the problem, reportedly found no other issues, changed the oil, and tried to burn the excess fuel out of the engine system.
That’s one of six times the vehicle has allegedly visited a Honda service department for oil dilution-related problems, and this complainant isn’t alone. Parsing the NHTSA complaint page, it’s not hard to find owners of vehicles newer than the alleged fix date that allegedly are experience serious oil dilution-related issues. Take this complaint from the owner of a 2019 CR-V:
Vehicle had a engine failure at 64,000 miles, vehicle was very well maintained by dealer, on time, I went in for a oil change drove in to the dealer, got vehicle back and 400 miles down the road had loud knock in the engine, dealer told me they saw metal shavings, possibly a spun bearing from oil dilution, they refuse to repair it as it’s passed the 60,000 warranty mark leaving me with a $6000 bill
As it stands, owners of affected Hondas have limited options. They can sell their vehicles and get into something without a documented oil dilution issue, or they can try to save up for a repair fund. Neither of these are ideal, especially considering the average Civic or CR-V driver doesn’t have cash to throw around on sudden vehicle changes or repairs.
It’s worth noting that if you live in a warm state and arrive everywhere with a warm engine, you may not experience oil dilution. However, if you’re in the market for a Honda with a 1.5-liter turbocharged engine to use as a short-distance daily driver, you probably want to think again. Remember, just because a company has a great reputation doesn’t mean it gets everything right. Just ask any owner of an early-aughts Accord V6 with an automatic transmission.
(Photo credits: Honda)
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Wow I thought I was reading about a BMW problem once I got into the article-what the hell Honda. I do worry that regardless of make all of these average-person turbo engines will have shorter lifespans on average than the NA engines they replaced-arguably offsetting their carbon footprint gains via emissions and mileage with shorter lifecycles. But time will tell.
OK, so I was thinking more about this today even though this article is off the front page. . .The way I understand it, the motor runs rich to help light off the cat and improve emissions at startup. This allows some unburn fuel to escape which can then be burned in the cat to more quickly increase the temperature.
This makes perfect sense. All is said and good when thinking about this from an old port injected stand point.
My question is, does this still makes sense with modern, direct injected engines? Why not, when the vehicle is cold, just give a little squirt during the exhaust stroke, allowing some fuel to be scavenged out the exhaust port. This will help light off the cat, without some of the downsides of running rich. Or is the combustion gas too hot at this point, leading to a second detonation?
Owners are left with limited options? Is driving your car for 30 minutes once every week or two not an option? Once oil reaches operating temp the fuel and water boil out of the oil. Problem solved.
What is oil operating temp and for which oil?
All I know is that engine oil works below 250°F and you would want to keep it below 250°F.
It takes 30 minutes on the highway for engine oil in my GTI to get to 190°F and once I saw oil temperature reach 210°F in the Chicago summer.
My wife’s car lived a quarter mile at a time…such a life is also VERY hard on the exhaust system.
Honda took too long to adapt to modern emission regulations I guess. I mean, they had the perfect base to work with, their classic 4-pots were so bulletproof.
There are so many things in my life that are chaotic, stressful, or unpredictable. The one thing I can always rely on is that NA K24 firing right up, no matter the temperature (-30C to 40C,) and always producing the same predictable smooth tone while climbing up through the revs.
Yeah, my 2011 CR-V is approaching 200k miles, and aside from the starter beginning to act up, is reliable as the day it rolled off the assembly line.
Ask any Subaru owner
Ask them what? About their deferred maintenance and blindly following what the dealer says (same guys that only read half the manual)?
AFAIK both Subaru and Honda have the regular OCI and severe OCI, and if you read the oners’ manual there is no regular service interval for any of them. A spec of dust or pollen in the air, sever service needs to be followed, air temps below 50 or above 80F, severe service.
I did not have any issues with dilution of the oil in the WRX until I installed an air-oil-separator. After that i can always see condensation in the crankcase.
I am not sure about the newer Hondas, but my 2015 odyssey opens up the thermostat at 160F and any Subarus past 2000s open at 192F.Also, the Subies heat up a lot faster
This is the way. Follow severe service intervals and the engine is usually happy. Also, most ‘regular’ driving in the U.S., as you stated, is “severe” driving. Not just for Subaru but for pretty much every manufacturer.
If you’re driving so many short distance trips that you risk destroying your engine this way you are a great candidate for a cheap, gently used compliance EV.
or just walk. it’s amazing how resistant the average person is to walking. There’s a KFC 2100 feet from my house (0.4 miles) and my friends will want to drive. Mostly because city design is terrible, I don’t blame people but it still annoys me sometimes.
Driving distances short enough where the engine never gets fully warm has always been a bad thing for ICE cars in general.
A 1992 Ford Escort my mom once owned and only drove short distances needed an engine rebuild at ~90,000km because the internals got rusted up and it dropped a valve.
Meanwhile a 1991 Escort I had with the same engine still ran fine with 346,000km on it because I would drive it enough to get fully warm daily.
And for some cars it’s especially bad… such as the Mazda RX8.
With that car, not only should you drive it so it fully warms up every time. There is a saying… “A redline per day keeps the mechanic away”. And that’s because getting it fully warm and then running the rotary engine to the redline at least once every time will prevent carbon buildup on the apex seals, which in turn avoids premature apex seal failure.
That saying applies to many cars… but doubly so for any rotary-engined car.
And this is another area BEVs are VASTLY superior to ICE vehicles. You can drive them short distances and not worry about having to warm them up or risking any long-term damage by not warming them up.
This. I’m less than four miles from my (soon to be former – anybody hiring?) office, which is why I was seriously considering an electric for my next car. Fortunately it’s a standard grid at streetcar-suburban density in the one part of the metro with visible investment in bike lanes, so it’s an easy and not too unsafe ride on a Class 1 e-bike instead.
I was fortunate when I worked at an office a little over a mile from my home that I was able to walk or use a bikeshare to commute rather than my car most days, and tried to stack it on days that I knew I’d want to take a longer drive later for errands (which were not in the same vicinity) – that was mostly to avoid carbon buildup from DI and general wear. My commute now is about 20 minutes and 10 miles which I wouldn’t consider a short trip, and it’s interesting to watch the digital readout for the oil temp on the trip computer – it’s usually not until about/over halfway through the drive when it finally crests 200 degrees.
Recently dumped my wife’s 1.5 2019 civic for this reason. Although, it NEVER did short trips. Its life was 40-mile commute, all highway (70mph), 2x a day. Oil changed religiously at 5k since new. At 90k-ish it started to smell like gas until oil change time. Oil was rather saturated with fuel on the last few oil changes. I changed the oil one last time at 105k, and dumped it for a Toyota Rav4. Our other 1999 and 2001 Honda civic’s went 300k and 200k without a problem. The days of the reliable civics (Honda’s?) are behind us sadly…
I’ve been told the 2.0 NA Civics are reliable. A cousin has owned a 2016 with that engine for the last 5 years, although hers just crossed 80K miles.
You are correct: my statement of the reliable Hondas might be behind us was probably uncalled for. If they do, in fact, offer a N/A version in lower trims in the future, that’d be great. Although, it looks like those will be going away due to CAFE standards.
Any used Nissan LEAF has entered the chat.
> ECU and TCU software updates
The source code of those updates:
def problem_detected(): return False
So this would be a bad choice for New York City alternate side of the street parking, is that what you’re saying?