Do you know somebody who is – how do we say it? – not great at taking care of a vehicle? Does their car consistently miss oil changes; get serviced too late; or not see a mechanic often enough? Based on our experience servicing a wide variety of vehicles every day, we’ve put together a list of engines that these type of car owners should shy away from. When maintained properly, these engines can be very reliable for a long time – but if their maintenance starts to lapse, it becomes a very different story.
In no particular order, here are our picks!
Fiat Chrysler 3.0L EcoDiesel
Ram 1500 Pickup, 2014 – Present
Jeep Grand Cherokee, 2014 – Present
Chrysler now uses the “EcoDiesel” name to describe two different 3.0L engines, but our focus here is the engine used in Jeep SUVs and Ram trucks, which comes from Italian engine design house VM Motori. (The other “EcoDiesel” engine is a Fiat design, used in the Ram Promaster vans.)
This engine was designed to provide better fuel economy than a gas engine would be able to achieve in a heavy truck or SUV; and it delivers on this promise. Where it starts to fall short, however, is reliability. The VM Motori EcoDiesel has been plagued with durability issues since its release, leading to some drastic actions from Chrysler in response. First the engine’s recommended oil viscosity was increased to 5w40 from the thinner 5w30 that the engine first used. Later, Chrysler released software changes for the engine’s computer which changed the torque curve at lower RPM, in order to take some pressure off the engine main bearings. While these changes have helped, the engine is still far from what we’d consider calling “robust”. Because – like all modern diesels – the engine is fitted with all kinds of very intricate and expensive parts, it’s an engine that owners should try to maintain as well as they possibly can.
At the time of writing this, the Ram EcoDiesel is currently on hiatus for the 2019 model year, with a revised version of the engine coming for 2020.
Hyundai/Kia 2.0L/2.4L Theta II
Many Hyundai and Kia models produced between 2010 and today.
Hyundai’s newest 2.0L and 2.4L engines power all kinds of popular Hyundai models between including the Santa Fe and Sonata, among others. Kia also uses the engines in a handful of vehicles including the Optima and Sportage. Between two separate recalls, Hyundai has now recalled almost 2 million vehicles in North America because their Theta II engine can start knocking or even seize because of a failed crankshaft bearing. All of the affected engines were produced in the same assembly plant in Alabama.
While many of the recalled engines fail because of debris left inside the engine from during their production, we’ve seen many more that probably failed early due to poor maintenance. Unlike many modern engines, these 2.0L and 2.4L engines only require a basic conventional oil, and therefore require an oil change every 6,000 kilometers – which is a fairly short interval for a modern car. If these intervals are consistently stretched out a little too long, or if cheap “lube shop grade” oil filters are used, then engine failure is much more likely to result.
Ford 6.0L Diesel
Ford F-250/F-350 Super Duty, 2003-2007
Ford Econoline, 2003-2009
Ford Excursion, 2003-2005
Even though Ford hasn’t produced the 6.0L diesel for over 10 years now, you still see a lot of them on the road – and that speaks mostly to how good the Ford Super duty trucks are. For years, you could make a good argument for the Ford Super Duty being the best truck on the road, if only it wasn’t for their engines.
Ford’s 6.0L engine, which came from International, could provide years and years of reliable service – but it could also develop into a very expensive, diesel-powered money pit. Failed fuel injectors; oil coolers; and high pressure oil pumps are just a few of the common problems that we still repair on these engines regularly. As we often see in this industry, the determining factor is maintenance. We’ve seen well-maintained 6.0s reach 300,000 km without any major repairs, and we’ve seen less well-maintained engines cost their owner tens of thousands of dollars within a couple years. The engine oil in a 6.0 has a lot of jobs to do. Besides lubricating the engine, it must also also lubricate & cool the turbocharger, and act as the hydraulic fluid in these engines’ complicated HEUI fuel injection system. Regular oil changes are a must with the 6.0, as these systems rely on a steady supply of quality, clean oil to protect all of their expensive parts.
Ford 4.6L & 5.4L Triton 3 Valve
Applications (partial list):
Ford Mustang GT, 2005-2010
Ford F-150, 2004-2010
Ford F-250/F-350 Super Duty, 2004-2008
Ford Explorer, 2005-2010
Ford Expedition, 2005-2014
Lincoln Navigator, 2005-2014
Ford makes our list again with another truck engine; possibly the worst engines installed in a truck within the past 20 years. Ford’s modular truck engine has been around for a long time; first offered in a 4.6L or 5.4L V8, and a 6.8L V10. Early versions of these engines were very tough and reliable, but that all changed with the introduction of the “3 valve” engines in 2004.
As their name suggests, these engines now used a new cylinder head design with 3 valves per cylinder. (These heads also employed a rather unique spark plug design that led to the spark plugs becoming stuck in the engines, but that’s a story for another day.) 2004 also marked the introduction of variable valve timing on these engines. While that technology is nothing special today, Ford’s first attempt at a VVT truck engine was considered a failure. These engines commonly experience problems with their timing chains; timing chain tensioners; camshaft phasers and other VVT system parts. These can be very expensive repairs, but it gets worse: the “bottom end” of these engines hasn’t proven to be very robust, and we regularly see cases where worn-out bearings result in an engine that’s not making enough oil pressure, and isn’t worth fixing. About half of the 4.6L and 5.4L engines that come through the shop with camshaft/timing chain noise engine up needing complete engine replacements.
Part of these engines’ fragility has to due with how oil flows inside them. Some of the oil passages inside the 3 valve engines are very small, and this is part of the reason why these engines use a thinner 5w20 engine oil. These small passages are prone to clogging when infrequent oil changes lead to varnish, sludge and debris build-up in the oil. This can starve important engine parts of their oil flow and cause many of the failures listed above. For this reason, these engines absolutely require clean oil that is changed every 5,000 km, and a premium oil filter used at all times.
General Motors 1.4L Ecotec Turbo
Chevrolet Cruze, 2011 – Present
Chevrolet Sonic, 2012 – Present
Chevrolet Trax, 2014 – Present
Buick Encore, 2013 – Present
With direct injection; variable valve timing; a turbocharger and an oil life monitor system that stretches oil changes out to over 15,000 km on occasion, this engine is hard on oil. This is partially because the engine only holds about four litres of oil, not much for such a high-feature mill. GM’s peppy 1.4L turbo engine can be a very reliable little powerplant, but only when oil changes are kept up regularly. Like the other engines in this post, the 1.4L Ecotec joins the short list of engines where we actually recommend changing the oil sooner than the manufacturer’s specified interval.
Turbocharged 1.4L Ecotec engines that don’t see regular enough oil changes usually experience early failure of their turbocharger; variable valve timing parts such as camshaft phasers/adjusters; and timing chains. All of these repairs aren’t cheap, so a little insurance in the form of regular oil changes will go a long way to keeping these small, hard-working engines running.
A little nagging from your mechanic:
With this post, we picked the five engines that, in our experience, absolutely require very regular oil changes. But how about engines in general? Has the oil change become more or less important than it used to be? The answer to that question depends on timing – when was the engine built?
For four decades between about 1970 and 2010, engines became more and more reliable. We certainly do a lot less engine repairs than we used to in our trade, and there’s no question that an engine built in 2005 is exponentially better than one built in 1985. That being said, around 2010 we reached the “peak” of engine reliability, and we’re now experiencing a bit of a decline again. That’s because with ever-tightening emissions and fuel economy regulations, plus consumers’ increasing desire for horsepower, car manufacturers are asking more from their engines than they ever have. Every driver wants their new vehicle to have more power than their previous car, but burn less fuel. That’s possible; but only with a lot of extra technology thrown into the mix – like direct injection; variable valve timing; turbocharging and more. This means that in a modern engine, your engine oil has a lot more work to do. Besides just lubricating the moving parts as it always has, your oil now acts as the hydraulic fluid inside the variable cam timing system and cools your turbocharger; among other jobs.
Because engines have become so much better over the years, many of us are a little too lazy with our oil changes these days. That needs to improve as today’s super complex (and super expensive) engines now require a little more careful maintenance.
Are you looking for a rock solid engine that doesn’t require much maintenance? Stay tuned as we have another Top 5 list coming soon; illustrating our picks for the most bomb-proof engines out there.