The lesser risk in a used Kia Optima is a CRDi diesel with receipts for regular oil changes, since the 2.0 and 2.4 Theta II petrols carry a known risk of bearing failure, seizure and fire.
3 known faults, 3 rated high severity in our database; owners report 49.0 mpg, 73% of the official figure. Everything below is built from that data and the archived owner history, not from a press car.
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Check a Kia Optima advert (free) →A CRDi diesel with receipts showing regular oil changes is the Optima to buy, because every engine with a known fault against this car has a serious one, and the diesel's is the one that's tied to servicing. Its turbo can fail when carbon from infrequent oil changes blocks the oil feed, whereas the 2.0 and 2.4 Theta II petrols can wreck their rod bearings, seize and carry a fire risk, and the 1.6 GDi's timing chain tensioner can fail and let the chain damage the engine.
On the 2016 to 2019 car, pick the DCT automatic: it's the gearbox that makes the Optima relaxed and comfortable on the motorway, and the manual feels slightly flimsy. Neither the diesel nor the PHEV has much pace, and the diesel's loud when it's worked hard. Cars built from 2017 to 2019 were recalled for a camera software update because the forward collision avoidance could miss stationary vehicles.
The 2012 to 2016 Optima shares those engine faults, and its manual clutch is the other thing to question. One owner's car had gear selection trouble at 22,000 miles, and 2014 Hyundai i40 manuals, which use the same drivetrain, had a clutch design problem, though it isn't clear whether Optimas were affected. Either way, don't buy a manual that's reluctant to go into gear.
No Optima engine with a known fault is a safe choice, and the CRDi diesel is the lesser risk as long as it has receipts for regular oil changes. Its turbo can fail between 70,000 and 120,000 miles when carbon from infrequent oil changes blocks the oil feed pipes and strainers. A loud whine or siren from the turbo, flat performance or blue smoke means it's already failing.
The 2.0 and 2.4 Theta II petrols are the ones to avoid: debris left in the crankshaft oil passages during manufacture can destroy the rod bearings between 60,000 and 120,000 miles, seizing the engine and creating a fire risk. If you still look at one, a knock that rises with the revs, stalling or a flashing engine light rules it out. The 1.6 GDi's chain tensioner can fail between 60,000 and 100,000 miles, so a cold-start rattle rules that one out.
On 2016 to 2019 cars, the DCT automatic is the gearbox to go for, since it's relaxed and comfortable, and at its best on the motorway. The manual feels slightly flimsy. One owner's manual had gear selection trouble at 22,000 miles and the dealer said it needed a clutch, and 2014 Hyundai i40 manuals, which share the Optima's drivetrain, had a clutch design problem that made gears hard to engage, though it isn't known whether the Optima's affected.
Hear the engine start from cold, since a rattle on a 1.6 GDi points to the timing chain tensioner. On a 2.0 or 2.4 Theta II petrol, a knock that quickens with the revs, stalling or a flashing engine light means the rod bearings are going, so don't buy it. On a CRDi diesel, a loud whine or siren from the turbo, or blue smoke from the exhaust, is the warning sign.
Get the service history and match it to the engine. Oil-change receipts at regular intervals matter most on a diesel, since infrequent changes are what block the turbo's oil feed. On a 2017 to 2019 car, ask for proof the recall was done: it updated the camera software because the forward collision avoidance could fail to spot stationary vehicles.
On a manual, try every gear from rest and on the move. A poor change or trouble getting into gear is the clutch symptom seen on 2014 i40s with the same drivetrain, and one Optima had gear selection problems at 22,000 miles. Check any glass sunroof for cracks too, since one owner waited more than six weeks for replacement glass after theirs was broken.
Paste the advert into the free check and it runs these against the listing, the MOT history and the DVLA record before you travel.
Engine failure is the big one: the 2.0 and 2.4 Theta II petrols can lose their rod bearings to manufacturing debris between 60,000 and 120,000 miles, the 1.6 GDi's chain tensioner can fail between 60,000 and 100,000 miles, and 1.6 and 1.7 CRDi diesels can lose their turbos between 70,000 and 120,000 miles once carbon from infrequent oil changes blocks the oil feed. That's why oil-change receipts matter so much on this car.
Beyond the engines, there isn't much on record. A 30-month-old Optima developed gear selection problems at 22,000 miles, and its owner was quoted £900 for a new clutch. Hyundai i40 manuals built in 2014, which share the Optima's drivetrain, had a clutch design problem causing poor gearchanges and trouble getting into gear, though it isn't known whether Optimas were hit. The 2017 to 2019 cars were recalled for a collision avoidance camera software update.
The 2016 to 2019 car has a five star Euro NCAP rating, but it's got a couple of drawbacks to feel for on the test drive. The engine sounds coarse if you rev it hard, the diesel's loud when you work it, and GT versions have an unsettled ride, so drive one over a rough road before deciding.
Real-world economy on this generation: Kia Optima 46.7 mpg, Kia Optima 50.8 mpg.
Sellers rarely admit these faults outright
Paste any Kia Optima advert and we check it against the faults, the MOT record and these figures in seconds.
Check an advert now (free) →Owners report 49.0 mpg across the Kia Optima engines with data, about 73% of the official figure, from 121 submissions.
Kia Optima Real MPG by engine →The 2016 to 2019 Optima's a great motorway car, and the DCT automatic makes it a relaxed, comfortable one to drive at those speeds. It feels solid on the road as well, and the automatic's the version that suits that easygoing character best.
The cabin's well built and the dashboard's intuitive, so it doesn't take long to find your way around the controls. Adults fit on the back seat, and there's plenty of space in the cabin and the boot, so carrying people and luggage isn't a squeeze.
The lesser risk in a used Kia Optima is a CRDi diesel with receipts for regular oil changes, since the 2.0 and 2.4 Theta II petrols carry a known risk of bearing failure, seizure and fire. Our database holds 3 known Kia Optima faults, 3 rated high severity, and the sections above say which generation and engine carry them.
Hear the engine start from cold, since a rattle on a 1.6 GDi points to the timing chain tensioner. Read the MOT history for repeat advisories and ask for invoices for any work the seller mentions. Then paste the advert into the free check, which reads it against every known Kia Optima fault before you travel.
Owners report 49.0 mpg on average, about 73% of the official figure, from 121 submissions. Chain (2.0 THETA, 2.4 THETA, 1.6 GDI): no fixed replacement interval, so budget for it if the history does not show it done. The known faults page lists a rough repair cost against each fault. Kia Optima Real MPG by engine.
If you used the Honest John car-by-car reviews before the site closed in 2026, this is where the Kia Optima buying advice now lives. It is written from the archived owner reports and model notes (archived page, 25 items read for this model), our own known-faults database, the confirmed service intervals and the Real MPG figures. Every number on the page comes from that data, not from the text. The same data feeds our free advert check.
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The Kia Optima is one decision. Reading the advert, the history and the seller are the rest, and these cover them.
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