Hyundai / Kia 2.4L Theta II GDI Engine Best Oil Sweet Spot

ChrisD46

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Actually, I do tend to agree with you on this. When I bought car in Dec 2020, the first oil change I did was with M1 5w30 ESP which is almost a w40. Now I've had Kirkland 5w30 for the last 5 months and 3-4k and I prefer the way the engine feels. I have yet to do a UOA but will in about a month. But the thing is there is no way youre going to see 1-2 mpg gains from such a miniscule difference in viscosity. You're better off using a high quality 5w20 in the winter unless short tripping.
*I still hold that I did see a slight increase in mileage from the "thinner" 5W30 synthetics in my Hyundai 2.4L GDI - but I can't count out either that Fall / Winter gas change over has something to do with this . I will also add that with a 5W20 synthetic - the Hyundai 2.4L Theta II runs like a "scalded dog" and was noticeably more responsive with throttle increases . Alas , the engine became quite a bit louder with 5W20 synthetic in it as well making me believe that a 20 weight oil just is not up to the task in this engine . Factor in fuel dilution , resulting in sheering and then questions of film strength and no wonder Hyundai / Kia dealers no longer use 20 weight oils in the 2.4L Theta II GDI engines .
 
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The post by Tom NJ in this thread is an excellent list of what affects measured gas mileage. I once linked an article that showed that even at the same gas station the energy density of gasoline can vary up to 4%. Remember it’s not measuring something that is the problem, the problem is being able to attribute it to an isolated variable. That’s where the real work comes in and that’s the thing that many people do not understand. It’s why the vast majority of “real world” tests are completely worthless upon close examination.

 
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*I still hold that I did see a slight increase in mileage from the "thinner" 5W30 synthetics in my Hyundai 2.4L GDI - but I can't count out either that Fall / Winter gas change over has something to do with this . I will also add that with a 5W20 synthetic - the Hyundai 2.4L Theta II runs like a "scalded dog" and was noticeably more responsive with throttle increases . Alas , the engine became quite a bit louder with 5W20 synthetic in it as well making me believe that a 20 weight oil just is not up to the task in this engine . Factor in fuel dilution , resulting in sheering and then questions of film strength and no wonder Hyundai / Kia dealers no longer use 20 weight oils in the 2.4L Theta II GDI engines .
😐🤣🤣🤣🤣🤣🤣🤣🤣🤣
 
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*I still hold that I did see a slight increase in mileage from the "thinner" 5W30 synthetics in my Hyundai 2.4L GDI - but I can't count out either that Fall / Winter gas change over has something to do with this . I will also add that with a 5W20 synthetic - the Hyundai 2.4L Theta II runs like a "scalded dog" and was noticeably more responsive with throttle increases . Alas , the engine became quite a bit louder with 5W20 synthetic in it as well making me believe that a 20 weight oil just is not up to the task in this engine . Factor in fuel dilution , resulting in sheering and then questions of film strength and no wonder Hyundai / Kia dealers no longer use 20 weight oils in the 2.4L Theta II GDI engines .
I wouldn't be concerned with fuel in an NA 2.4l engine unless you short trip exclusively. If so, just follow severe interval. Also a synthetic 5w20 is not going to shear as much as a synthetic 5w30.
I've picked an interval which is in between, 5k/6mo and this time I'll have a UOA afterwards. My driving consists of mostly city driving above 50 degrees and I don't short trip.
Depending on the ambient temps, there may be a benefit to running 5w20 since most wear is at startup. If I lived in a climate that had temps below freezing and parked outside, I wouldn't hesitate to run 0/5w20. There just really isn't that much of a difference in warm weather. But I would not run a w40 or a "euro" w30 for this engine. I had a similar experience when I owned a 2019 mx5. I thought M1 ESP 5w30 was the bees knees. That low hp engine ran sluggish and I immediately went back to 0w20.
 

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Yup different oils have an effect on throttle response. Not sure exactly the contributing parameter, however, the less viscous 30wts such as ILSAC defiantly enhance the response which for me is a tangible consideration.
 
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I ran 5w30 PUP in my Hyundai Accent
I run everything from 5w30 to 5w50 in my Accent. xW40 seems to be the sweet spot for fuel economy vs wear protection (except 15w40 for some reason, always get worse mpg with that). Have some Valvoline 20w50 I got on sale that I will happily run next summer too. My experience is they definitely run better and make less noise with thicker oil, and will happily run just fine even on the very thick stuff.

166,300 miles and climbing, to the tune of 1200 miles a week.
 
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There is some evidence that manufacturing problems are a problem air instead of fluid machining swarf removal et al. But others Korean and Eastern Europeans are pointing to the variable oil pump situated in the balance shaft module. My tgdi theta2 2011 sonata se sees mostly 40 weights in summer and 30s in winter. 122k miles with a stage 2 tune 300 hp and dual catch cans.
 
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Boy do I have some bad news for you. I switched to 5w30 Mobil 1 vs. 5w20 around 4 years ago in our 2011 Sonata with the 2.4, and it went bang on my daughter like a month ago. It's not the oil, I promise. BTW, the expected turnaround for the lifetime warranty engine replacement is like 2-4 MONTHS.
 
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In our 13 Sonata 2.4L, i like to use Mobil 1 synthetic EP 5W20 in winter, and Mobil 1 EP 5W30 in summer & OEM Hyundai filter. 50K miles, no oil consumption, and change it every 5-6K miles. The engine sound very smooth and happy lol.
 
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There is some evidence that manufacturing problems are a problem air instead of fluid machining swarf removal et al. But others Korean and Eastern Europeans are pointing to the variable oil pump situated in the balance shaft module. My tgdi theta2 2011 sonata se sees mostly 40 weights in summer and 30s in winter. 122k miles with a stage 2 tune 300 hp and dual catch cans.
The boosted Hyundai /Kia's have much robust internals.
 
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Boy do I have some bad news for you. I switched to 5w30 Mobil 1 vs. 5w20 around 4 years ago in our 2011 Sonata with the 2.4, and it went bang on my daughter like a month ago. It's not the oil, I promise. BTW, the expected turnaround for the lifetime warranty engine replacement is like 2-4 MONTHS.
Connection rod bearing? Hyundai extended engine warranty to 150k miles, try asking dealer for a new a engine.
 
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Connection rod bearing? Hyundai extended engine warranty to 150k miles, try asking dealer for a new a engine.
Yep, bottom end locked up. Hyundai and Kia actually got sued into warranting those engines forever, as in 999,999 miles, and as part of the judgement they're required to either supply you with a loaner car or $40 per day for a rental.
 

ChrisD46

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Yep, bottom end locked up. Hyundai and Kia actually got sued into warranting those engines forever, as in 999,999 miles, and as part of the judgement they're required to either supply you with a loaner car or $40 per day for a rental.
*This is what I had read as well ... The main culprit are the connection rod bearings - best you can hope for is : 1) Use a good 5W30 oil to ensure enough film strength 2) Keep oil level on new "orange" dip stick up to the Full mark 3) Use a reasonable OCI (5,000 miles max) .
 

ChrisD46

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My parents 2017 Sportage blew up today. 60,000 kms on it and its in limp mode with the flashing check engine light. Always had synthetic oil. No more than 5000 kms on the oil. What a piece of poo.
*That's bad news - sounds like they did everything right yet the engine still gave way .
 

twouvakind

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Exactly...now for the doubling down whereby the multitudes claim this is not only possible but reasonable since they too can tell the difference...lol. There is a form of mental illness that runs rampant on BITOG.
With the OP and all it's detail, I have no reason to doubt your research, trials and tribulations. Good job!
 

CKN

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Yes , any oil I ran with a cSt at 11.0 and over was noticeable to require more throttle to get moving also requiring more noticeable down shifting .
Hyundai 2.4L oil cap says 5W20 and OM allows for 5W20 , 5W30 & 10W30 ... Folks should run what ever makes them happy . Castrol EDGE EP comes in at cSt @ 100 degrees C. of 10.8 and HTHS of 2.9 . Admittedly , I have not tried this oil yet .
This is nonsensical.......
 
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