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

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*I have tested various 5W20 , 5W30 and 10W30 synthetic oils in my 2017 Hyundai Sonata 2.4L . With 5W 20 weight synthetic oils the 2.4L Theta II engine runs nice and free - but due to fuel dilution and potential rod bearing issues - the question of not enough film thickness is often discussed as these engines continue to fail , so no wonder Hyundai / Kia now have gone to 5W30 oils for more film thickness head room . So, next I have experimented with thick 5W30 synthetic oils which Hyundai / Kia have now turned to in this engine (up to cSt @ 100 degrees C 12.0) as well as thin 5W30 synthetic oils down to cSt @ 100 degrees C 9.8) . The verdict ? The best running 5W30 synthetic oils in my Hyundai 2.4L Theta II engine have a cSt @ 100 degrees C. of between 9.8 to 10.6 (PPPP 5W30 , Valvoline Advanced 5W30 and M1 5W30 EP) . When I use thicker 5W30 synthetic oils greater than cSt @ 100 degrees C. of 10.6 from 11.0 to 12.0 (QSUD 5W30 , M1 vanilla 5W30) , I notice the engine starts to strain more (especially when cold) and over all performance starts to suffer as if the engine is straining more to pump the thicker oils . Lastly , I have checked my gas mileage and approx. 1 to 2 MPG improvement with the thinner 5W30 synthetic oils with this engine . As with anything , variable do exist - I'm just throwing it out there that from my experience after almost 5 years with this engine the "Goldie Locks" sweet spot synthetic oil for this 2.4L GDI Theta IIGDI engine is to pick a 5W30 synthetic D1 / Gen 2 or 3 with a cSt @ 100 degrees C. of between 9.8 (PPPP 5W30) and 10.6 ... I myself feel the best compromise in this engine as far as protection cushion with performance considered over a 5K mile OCI are the Valvoline 5W30 Advanced / EP and the M1 5W30 EP with 10.5 and 10.6 cSt @ 100 degrees C. respectively .
 
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*I have tested various 5W20 , 5W30 and 10W30 synthetic oils in my 2017 Hyundai Sonata 2.4L . With 5W 20 weight synthetic oils the 2.4L Theta II engine runs nice and free - but due to fuel dilution and potential rod bearing issues - the question of not enough film thickness is often discussed as these engines continue to fail , so no wonder Hyundai / Kia now have gone to 5W30 oils for more film thickness head room . So, next I have experimented with thick 5W30 synthetic oils which Hyundai / Kia have now turned to in this engine (up to cSt @ 100 degrees C 12.0) as well as thin 5W30 synthetic oils down to cSt @ 100 degrees C 9.8) . The verdict ? The best running 5W30 synthetic oils in my Hyundai 2.4L Theta II engine have a cSt @ 100 degrees C. of between 9.8 to 10.6 (PPPP 5W30 , Valvoline Advanced 5W30 and M1 5W30 EP) . When I use thicker 5W30 synthetic oils greater than cSt @ 100 degrees C. of 10.6 from 11.0 to 12.0 (QSUD 5W30 , M1 vanilla 5W30) , I notice the engine starts to strain more (especially when cold) and over all performance starts to suffer as if the engine is straining more to pump the thicker oils . Lastly , I have checked my gas mileage and approx. 1 to 2 MPG improvement with the thinner 5W30 synthetic oils with this engine . As with anything , variable do exist - I'm just throwing it out there that from my experience after almost 5 years with this engine the "Goldie Locks" sweet spot synthetic oil for this 2.4L GDI Theta IIGDI engine is to pick a 5W30 synthetic D1 / Gen 2 or 3 with a cSt @ 100 degrees C. of between 9.8 (PPPP 5W30) and 10.6 ... I myself feel the best compromise in this engine as far as protection cushion with performance considered over a 5K mile OCI are the Valvoline 5W30 Advanced / EP and the M1 5W30 EP with 10.5 and 10.6 cSt @ 100 degrees C. respectively .
So you say you are able to detect engine straining and performance suffering within a single grade?

Plus a 1-2 MPG difference that you are attributing to the same viscosity change in the grade?
 
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This is what I have found to run the best in the 2.4L.
527234DF-7A72-40DF-B3C6-1D7A1C30F78C.jpeg
4653E62E-D118-4C51-907E-260DFA16401E.jpeg
 
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So you say you are able to detect engine straining and performance suffering within a single grade?

Plus a 1-2 MPG difference that you are attributing to the same viscosity change in the grade?
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.
 
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So. Calif.
Have settled on PUP 5W30 for my 2015 Kia Optima EX (2.4L, non-Turbo). Thought about using Mobil 1 ESP 5W30 but the cost and possible performance hit from higher cSt kept me from doing so.
 

FZ1

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Feb 7, 2008
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*I have tested various 5W20 , 5W30 and 10W30 synthetic oils in my 2017 Hyundai Sonata 2.4L . With 5W 20 weight synthetic oils the 2.4L Theta II engine runs nice and free - but due to fuel dilution and potential rod bearing issues - the question of not enough film thickness is often discussed as these engines continue to fail , so no wonder Hyundai / Kia now have gone to 5W30 oils for more film thickness head room . So, next I have experimented with thick 5W30 synthetic oils which Hyundai / Kia have now turned to in this engine (up to cSt @ 100 degrees C 12.0) as well as thin 5W30 synthetic oils down to cSt @ 100 degrees C 9.8) . The verdict ? The best running 5W30 synthetic oils in my Hyundai 2.4L Theta II engine have a cSt @ 100 degrees C. of between 9.8 to 10.6 (PPPP 5W30 , Valvoline Advanced 5W30 and M1 5W30 EP) . When I use thicker 5W30 synthetic oils greater than cSt @ 100 degrees C. of 10.6 from 11.0 to 12.0 (QSUD 5W30 , M1 vanilla 5W30) , I notice the engine starts to strain more (especially when cold) and over all performance starts to suffer as if the engine is straining more to pump the thicker oils . Lastly , I have checked my gas mileage and approx. 1 to 2 MPG improvement with the thinner 5W30 synthetic oils with this engine . As with anything , variable do exist - I'm just throwing it out there that from my experience after almost 5 years with this engine the "Goldie Locks" sweet spot synthetic oil for this 2.4L GDI Theta IIGDI engine is to pick a 5W30 synthetic D1 / Gen 2 or 3 with a cSt @ 100 degrees C. of between 9.8 (PPPP 5W30) and 10.6 ... I myself feel the best compromise in this engine as far as protection cushion with performance considered over a 5K mile OCI are the Valvoline 5W30 Advanced / EP and the M1 5W30 EP with 10.5 and 10.6 cSt @ 100 degrees C. respectively .
Great info from REAL experience. Thank you so much!
 
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Feb 3, 2020
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Los Angeles
*I have tested various 5W20 , 5W30 and 10W30 synthetic oils in my 2017 Hyundai Sonata 2.4L . With 5W 20 weight synthetic oils the 2.4L Theta II engine runs nice and free - but due to fuel dilution and potential rod bearing issues - the question of not enough film thickness is often discussed as these engines continue to fail , so no wonder Hyundai / Kia now have gone to 5W30 oils for more film thickness head room . So, next I have experimented with thick 5W30 synthetic oils which Hyundai / Kia have now turned to in this engine (up to cSt @ 100 degrees C 12.0) as well as thin 5W30 synthetic oils down to cSt @ 100 degrees C 9.8) . The verdict ? The best running 5W30 synthetic oils in my Hyundai 2.4L Theta II engine have a cSt @ 100 degrees C. of between 9.8 to 10.6 (PPPP 5W30 , Valvoline Advanced 5W30 and M1 5W30 EP) . When I use thicker 5W30 synthetic oils greater than cSt @ 100 degrees C. of 10.6 from 11.0 to 12.0 (QSUD 5W30 , M1 vanilla 5W30) , I notice the engine starts to strain more (especially when cold) and over all performance starts to suffer as if the engine is straining more to pump the thicker oils . Lastly , I have checked my gas mileage and approx. 1 to 2 MPG improvement with the thinner 5W30 synthetic oils with this engine . As with anything , variable do exist - I'm just throwing it out there that from my experience after almost 5 years with this engine the "Goldie Locks" sweet spot synthetic oil for this 2.4L GDI Theta IIGDI engine is to pick a 5W30 synthetic D1 / Gen 2 or 3 with a cSt @ 100 degrees C. of between 9.8 (PPPP 5W30) and 10.6 ... I myself feel the best compromise in this engine as far as protection cushion with performance considered over a 5K mile OCI are the Valvoline 5W30 Advanced / EP and the M1 5W30 EP with 10.5 and 10.6 cSt @ 100 degrees C. respectively .
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.
 
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My experience as a reference...
2011 Sonata Hybrid, also a Theta2 engine but with MPI, all the oil I used are thin. Latest UOA for Valvoline EP 5w30 shows cSt at 9.71. Before that I use Valvoline HM FullSyn 5w20, only has cSt at 8.35. Both UOA show excellent wear protection at 3500 OCI.
How much metal in your used oil OP? Mine has 2ppm aluminum, 2ppm iron and 1 ppm brass, however I'm not sure it's because of the oil or MPI wear slower. I'm running 0w20 now for testing.
 
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Cumberland County, Pennsylvania
My '19 2.4L Theta specs 5w-20. I've also run 5w-30 in it--there's no humanly detectable difference between the two in my opinion, regardless of ambient temperatures. I run 5w-20 pretty much year round now just to simplify my oil purchases (I own a truck that also specs 5w-20). My son's turbo Theta gets 5w-30 as that's what it's spec'd for. I recently put fresh Valvoline 5w-20 AFS in the 2.4L. . . Next spring I'll try to remember to get a UOA of this OCI--this vehicle will see daily short-tripping in cold weather with some commutes on interstate and local roads. Stay tuned!
 
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I've used PP 5w-30 in Sportage in the past 60K miles with great results, but last OC was with Kirkland Synth 5w-30. It actually started burning oil 2/3 in on last OC (OCI are 4K miles). Next OC will be with RGT 5w-30.
 
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Used R.G.T. ( S.N.+ , GF-5 ) 5w-30 from spring to few weeks ago and now using R.G.T. 5w-20 ( S.N.+ , GF-5 ) hopefully until April or early May of '22 . This is '18 ACCENT w/ 1.6 Ltr. , G.D.I.. No change in gas mileage .
 

ChrisD46

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So you say you are able to detect engine straining and performance suffering within a single grade?

Plus a 1-2 MPG difference that you are attributing to the same viscosity change in the grade?
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 .
 
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