2015 Kia Optima LX QT/300 Miles Oil Burned Solved/Fixed

This is my first post here so hello everyone. Little about me: I'm a wrencher who likes to DIY to save money and to have a peace of mind that the job will get done right. I can do most of the combustion engine car maintenance, save for taking the engine out. I do not have the garage space for that or the tools to do that.

I've had dealings mostly with port injected engine cars so I never came across an oil engine burning problem.

Totaled my daily driver Honda, bought a 2015 Kia Optima LX with 103,000 miles on it in a very clean condition inside and out. I had to change the brake pads, rotors, shocks in the rear, eventually tires for the winter weather here in IL, air filter, cabin filter, wiper blades... simple stuff. Well, the rear rotors were a bit of a surprise because I had to undo the bolt for the control arm and move it out of the way to be able to remove the rotor. Fine.

I did my due diligence when it came to research regarding recalls and engine problems. My Kia had a recall for the HECU unit and everything checked out fine at the dealership. There wasn't an engine recall on the Kia I bought. I wanted to take a risk because used Hondas and Toyotas this past summer had outrageous pricing and the Kia was just right.

During my weekly and sometimes my bi-weekly fluid check, I noticed that the Kia burned a quart of oil per 300-400 miles driven and that it burned the oil much faster during highway driving. So...

Here's how I fixed the engine oil burning problem:

2015 Kia Optima LX 2.4L 4 Cylinder

Upon inspection before taking on these DYI fixes, I did inspect the valve cover and the oil pan and there was no visible leaks. Everything was/is bone dry in that department. I proceeded to do further research why the Theta II engine is burning so much oil and I came across many complaints regarding these engines, dealerships stating that even qt/1000 miles driven oil consumption is normal (what?), and I came across the Kia technical service bulletin 222 which is essentially a repair guide for Kias with an excessive oil consumption problem.

Before the DIY listed below I did replace the PCV valve that I got from the dealer. I did look into oil catch cans as well, but decided I did not want to deal with additional maintenance, e.g. forget to empty it, winter freezing it, etc. Besides I don't think an oil catch can would fix qt/300 engine oil burned. I also changed the spark plugs to NGKs Iridiums. There was a bit of engine judder at idle before the DYI listed below, but otherwise the engine was operating quietly and normal.

First I started doing research and came across this blog: https://motoroilbasics.com/preventing-and-addressing-oil-burning-problems-in-a-gdi-engine.php

The first attempt: I followed the 5-step directions (with my own twist) of the blog listed above. At first I used Royal Purple Max-Clean in the gas tank. I then used Berryman 2611, finished the first cycle of directions, came back to the garage, and finished the second cycle of directions. I did encounter loss of power and the engine struggling to rev up right after the treatment, but that goes away after a few miles and some highway driving. I decided to perform an engine flush next with Liqui Moly 2037 and I followed the directions precisely as this was my first engine flush. Before the flush I checked the oil level and made sure it was reading FULL. I didn't want to throw a rod because of lack of oil. I drained the oil and replaced it with new 5W-20 Castrol Edge Advanced Full Synthetic and used an OEM 26300-35505 oil filter. After driving for 300-400 miles, the car still continued to burn a quart of oil per 300-400 miles driven. I drove for about a 1000 miles, adding oil in the process, before I repeated this process.

The second attempt: I followed the 5-step process from the first attempt, but the only thing I changed was the engine flush to BG 109 EPR and instead of using Royal Purple Max-Clean I used Techron Complete Fuel System Cleaner 12oz which was enough for the 18.5 gallon fuel tank that my Kia has. The rest of the process remained the same. Unfortunately, there was no change in the oil burning rate. At this point I started to worry that I might have to spend a few $K to change piston rings or worse, the engine. So I started doing more research to avoid an expensive visit to a mechanic.

After more research, I decided to buy Kano Kreen to perform a piston soak, and at this point I decided to add PEA based cleaners to every fresh fuel tank despite what people may say/recommend on the forums. I did not bother with non-PEA based fuel injector cleaners. When using Techron, business was as usual when engine was running. Gumout Regane made the idle a little wonky, but no big deal. Redline SI-1 exhaust can really stink like rotten eggs. That's a confirmed from other forum postings using it. I also used Royal Purple Max-Atomizer, 2 bottles at once, the engine ran fine. I eventually went back to Techron Complete Fuel System Cleaner 12oz and just stuck with it throughout the DIY process.

So onto Kreen. Smells powerful, must be powerful then, no?

The third attempt: I bought the one gallon can of Kreen. I followed the directions on the Kreen can. I removed the spark plugs, poured 2 oz of Kreen in each cylinder, removed the fuel pump fuse, as you don't want fuel being pumped into the chamber, cranked it twice at a few seconds each, poured more Kreen in, and replaced the spark plugs to prevent evaporation. I performed the soak for one day and checked the Kreen level in the cylinders with the Innova Inspection Camera borescope that I got from Auto Zone throughout the day. I added a few more oz throughout the day making sure the cylinders were filled with Kreen and completely covered. Usually 2 oz at a time in each cylinder. Kreen was disappearing at a slow rate. The next morning I decided that I'll do one more day of soaking and finally fire the engine up at night so nobody can see the smoke grenade effects coming out of the exhaust.

NOTE: Kreen either evaporated or made its way to the crankcase so I replaced the engine oil after the smoke show. I was still using 5W-20 Castrol Edge Advanced Full Synthetic and a new OEM oil filter at every change, but I changed to 5W-30 at this stage, but this time I poured 4 quarts into the crankcase and a quart of Kreen. The engine oil capacity of the 2.4 in my car is 5.07 quarts per the manual. Because I would be driving the car with Kreen in the crankcase, which was a little nerve wracking, I checked the oil level everyday. The car was driven for about a 1000 miles with Kreen in the crankcase and oil was added daily and kept at the FULL mark. After 1000 miles, the oil was changed with a 5W-30 oil, still Castrol, and an OEM oil filter.

There was no change in the oil burning rate. At this point I started having a conversation with my wife for a potential piston ring job (or other...) and how much it would cost and it wasn't a particularly great conversation because there was disappointment in the air regarding the car, but I did not give up yet and after more research I decided on the ultimate weapon in the universe when it comes to piston soaks.

Berryman 0116 B-12 Chemtool was/is the right tool for the job.

I also did more research regarding oils and came across 540 Rat blog regarding oils (https://540ratblog.wordpress.com/). I chose the most powerful oil to exist to help me: 5W30 Quaker State “Full Synthetic” with a 152,674 psi wear rating. I'm not an expert here, again I'm just a DYI wrencher, but you can't go wrong with an oil that costs less than $20 with such incredible wear protection rating.

The FIX fourth attempt: I packed my tools in the car and went over to my dad's where there's more space. I live in a condo with a garage, but the garage is tiny. I decided that I will do the soak for about 5-7 days. First day, I got the car up on car service ramps so I could change the oil easily after the soak. Got the spark plugs out, emptied the entire can of B-12 Chemtool between 4 cylinders equally, DID NOT CRANK the engine (B-12 Chemtool is not a lubricant), replaced the spark plugs to prevent evaporation, had a beer with dad, and left for the day. Came back the next day, checked the Berryman B-12 levels and 2 cylinders out of the 4 cylinders were empty. I added more, replaced the spark plugs, beer again, and left. This is day 3 now. Berryman B-12 levels are stable in the cylinders, still full. Day 4, same. I took this as a good sign and assumed the rings got free. Day 5 I got a Brake Bleeder Pump Kit from Harbor Freight (https://www.harborfreight.com/brake-bleeder-and-vacuum-pump-kit-63391.html) to get as much Berryman B-12 out of the cylinders as I could. Halfway through pumping the Berryman B-12 out, the brake bleeder pump gasket got very malleable and soft and I had to make a duct tape gasket to continue pumping Berryman B-12 out. Acetone, check. The rest of the tool was unaffected. After some time the gasket returned back to its normal size and sealed again and the tool was usable again with the original gasket. There was probably no lubricity left in the cylinders anymore after the B-12 soak, but wow, the piston tops looked completely clean. I decided to nuke it (soak it) with Kreen for 2 more days to restore some lubricity and because why not, I had Kreen laying around and it seems that the concensus is, if you have it, use it. Poured a couple oz in each cylinder, left it for the day, came back the next day. Day 6, each cylinder is still wet and covered with Kreen. Day 7, I pumped the Kreen out with the brake bleeder pump. Kreen did not affect the gasket in the bleeder pump. I removed the fuel pump fuse, I cranked the engine to remove the excess Kreen. I cranked it twice for a few seconds each with a break in between. After a quick borescope inspection the cylinders were fairly dry. I cut to size and wrapped a microfiber cloth around a screwdriver and duck taped the cloth to the screwdriver to clean out the spark plug holes as there was an ungodly amount of carbon on them/on the walls where the spark plug coils go. I didn't want to replace the spark plug coils when there was such a mess in those spark plug hole/areas. I put the spark plugs back in, then the coils, I put the fuel pump fuse back in, cranked the engine for a few seconds until it started and man... this smoke show was way more intense than the first one. Definitely got looks from passerbyers.

I ran the car until the smoke show stopped. Turned it off. Changed the oil (5W30 Quaker State “Full Synthetic”) and oil filter with the OEM one while the engine was still nice and warm. Fresh oil check, new oil filter check. Hands slightly burned. JK, I used gloves. Now, I poured BG 109 EPR into the fresh oil and ran it for 30 minutes at the recommended RPM. Drained, changed the oil, used Quaker State, changed the oil filter again with an OEM one, added BG MOA 110 and that seemed to fix the oil burning problem.

After all this torture I also changed the spark plugs to DENSO Iridium ones that are recommended for the engine. This was a second spark plug change, and it probably was not necessary, but the amount of PEA that went through the combustion chamber triggered my OCD so I changed it. The engine judder at idle disappeared and the engine felt like it gained more power, even the wife said so herself.

I drove a full 5K miles without any oil consumption. After 5K miles I changed the oil again with Quaker State and again added BG MOA 110 and after 3K miles there has been no oil consumption. MPG was right on specs around 23 city/suburbs and 30-31 on the highway, not to say that MPG was not on specs before this DYI job. It was around the same, but even more sometimes, probably because I was using 5W-20.

The takeaways: Maybe it would have been easier to do the piston job, but this little science experiment was still cheaper at around $300-400, I stopped keeping track after a while, vs. a way more expensive piston ring job. And I have no scientific evidence that it was the piston rings all along that were the issue, even though after quite a bit of research, that would appear to be the problem. The reason I wrote this wall of text is because there was no clear directions/answers how to approach this problem when I was looking for an answer in one place. I am not aiming for this wall of text to be the ultimate solution, but a consolidation of about two months of research into one post of how one would go about an oil engine burning problem and how to fix it. The steps outlined above are not set in stone and not 100% on how one should perform a piston soak. Some research is still necessary, watching YouTube videos may help, and well, some common sense is definitely necessary as well.

Why not Marvel Mystery Oil?
After doing some research I was led to believe that MMO is mild vs Kreen and Kreen seems to be milder than B-12 Chemtool. I also watched a person trying to rescue his Honda's piston rings with MMO without success. He had to tear the engine apart and change the piston rings. Here's the video:

So I decided to use heavy hitters and it worked.

Why not non-PEA fuel injector cleaners?
PEA cleaners were recommend for GDI engines so I used those.

NOTE: The entire process took about 5K miles to complete. There was A LOT of highway driving involved. My wife works 60 miles away one way and it's 60 miles of highway, 5 days a week, though she works from home as well so it's not so bad. That could have contributed to the fix as well. We took the car to other states too for fun, monitoring oil of course, and before the FIX step, it was burning oil. Sometimes redlining was incorporated as well, as well as driving on the highway at a lower gear to keep the RPMs high to possibly help break up carbon, but I did that maybe once or twice, the lower gear driving. Again, not scientific, just forum recommendations. Right now the car has 115K miles and from 108K miles up till now there was/is no oil consumption. Knock on wood, I hope that with maintenance, the addition of PEA based fuel injector cleaners (I recommend Techron Complete and Rislone Hy-per Fuel), good Quaker State "Full Synthetic" oil, and a little BG MOA 110, I will not have to deal with the oil burning creeping its way back. I plan to just change the oil at the next oil change and the filter and see what happens. It's possible that BG MOA 110 was the ultimate fix, all of the DIY steps combined contributed to the fix, or maybe it was the fourth step that fixed it, I cannot scientifically and decisively pin point the fix despite saying that step 4 was the FIX, but judging how B-12 and Kreen stopped making its way past the piston rings and remained in the cylinder chambers for a few days does offer a possible logical explanation that piston rings got free thus preventing the oil getting in the combustion chamber to be burned off. I'm just happy that it's fixed and the car no longer feels like a disappointment.

Also remember to do your own research before attempting DIY fixes. Good luck!

Here are the links to some of the RESEARCH I've bookmarked for reference:

Preventing and Addressing Oil-Burning Problems in a GDI Engine​


Keeping GDI and T/GDI Intake Systems Clean​


Kreen Update​


Not your normal oil change​


Berryman's B12 chemtool /fuel system cleaner and piston soak precaution?​


Freeing up dirty, stuck oil control rings?​


Kreen recommended, why not Chemtool B12?​


Piston Soak - Now no compression

Excellent! I think these Korean cars have oil problems because of what they warn against in the owner's manual..Ethanol in gasoline. Amazing, but they list several negatives but then say, because the US EPA says it's ok you can use it.