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2011 Forte SX 2.4L (thankfully MPI) A/T 144K miles
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Thanks for the clarification, and full credit to you for being way out in front of the pack.
 

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2017 Kia Sportage SX
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I can say from experience over 3 different cars now that used GDI (my last 3 vehicles, 2006 mazdaspeed3, 2011 hyundai sonata 2.0T and last 2013 Genesis coupe 3.0 track) you will very likely NOT have any issues with the GDI.

This has been a combined amount of 300,000 + miles I have driven a GDI engine, 2 turbocharged, 1 naturally aspirated, I have had ZERO engine issues of any sort. Specifically I know the 2.0 Theta engine well since it was in my sonata. Anyone questioning this, know full well if you are a responsible driver, and maintain your vehicle properly, using reliable gasoline sources there will not be any problems. A bottle of Techron run through it every 3 or 4 months wouldn't hurt, but probably not needed either.

Now if you drive short distances, and never let it warm up I can't speak for that, but it causes problems on regular fuel injected engines too, so you know what to expect there.

If you don't mind spending just a little more on the oil, I highly recommend Pennzoil platinum, as it will keep your engine squeaky clean on the inside. All three of my previous vehicles ran that exclusively, and they were clean like new under the valves after my 100,000 miles of use.


In regards to catch cans, they are not really needed, and a lot of hype to be honest. Not to mention, you will need to be getting under the hood and emptying them on a regular basis or it will spill everywhere and make a mess.
 

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2014 Sportage SX FWD
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220 Posts
I can say from experience over 3 different cars now that used GDI (my last 3 vehicles, 2006 mazdaspeed3, 2011 hyundai sonata 2.0T and last 2013 Genesis coupe 3.0 track) you will very likely NOT have any issues with the GDI.

This has been a combined amount of 300,000 + miles I have driven a GDI engine, 2 turbocharged, 1 naturally aspirated, I have had ZERO engine issues of any sort. Specifically I know the 2.0 Theta engine well since it was in my sonata. Anyone questioning this, know full well if you are a responsible driver, and maintain your vehicle properly, using reliable gasoline sources there will not be any problems. A bottle of Techron run through it every 3 or 4 months wouldn't hurt, but probably not needed either.

Now if you drive short distances, and never let it warm up I can't speak for that, but it causes problems on regular fuel injected engines too, so you know what to expect there.

If you don't mind spending just a little more on the oil, I highly recommend Pennzoil platinum, as it will keep your engine squeaky clean on the inside. All three of my previous vehicles ran that exclusively, and they were clean like new under the valves after my 100,000 miles of use.


In regards to catch cans, they are not really needed, and a lot of hype to be honest. Not to mention, you will need to be getting under the hood and emptying them on a regular basis or it will spill everywhere and make a mess.
I'm on board with all of above, with one exception. Having a "Catch Can" or oil air separator is better than not having one. As long as, as you mention, the owner of the car is diligent and capable of periodically emptying it.
In my mind crankcase oil shouldn't be introduced into the induction tract. Especially in a car that's turbocharged. So far in the course of 28k mi's my 2.0t has dumped between 8 and 9oz's into my oil/air separator. That might not sound like much but who wants an oil slick that doesn't get washed out in their intake path knowing that gdi engines are prone to having intake valve deposit accumulations, and possible issues resulting from it.
A lot of folks only hold onto a car for 3-5yrs, they, will in all likelihood never need to be concerned with any gdi specific issues. So they needn't be concerned with doing anything but OEM suggested maintenance.
 

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2017 Kia Sportage SX
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The point I was mainly getting to, carbon buildup is simply not an issue to be concerned with on the 2.0T engine used by hyundai / Kia

They have designed the engine to inject fuel in such a way that it does in fact get some onto the backside of the valves so major buildup doesn't get a chance to accumulate. This is a common technique on the more recent engine designs and is used by several different companies, This is what has been determined to work best to reduce the deposits. This method is done by injecting fuel during the cycle where the valve is in the open position so that a mist of fuel / air does get exposed to the valves while they are open. While not as good as fuel coming down into the chamber through the valve, the exposure is enough to resolve the problem.

So now we know that buildup won't be an issue, then look at the downsides of a catch can being in there, this is a high maintenance item that being neglected can cause a serious fire hazard. Also, many of the cheaper designs available are prone to vacuum leaks which causes all other sorts on not really fun stuff to happen. If you suffer from the machining issues on the crankshaft that causes main bearing failure due to metal shavings, and you drop it off at the dealer with that catch can on it, they can grab onto that as a "cause" for the problems and make you pay repairs yourself instead of a warranty repair. Granted, the metal shavings issues have reportedly only affected 2% of these engines overall, but you never know.

From the time I have spent reading this forum, I can safely assume that most people on here are not up to the task of monitoring an oil catch can on a long term basis. Yes, there are some here who would have no problem with it, but as far as a recommendation to everyone, not a great idea. It appears that 10% of the folks on the forum do a lot of self maintenance, the rest are going to the dealer or a private shop for all their work needing to be done.
 

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Kia PRO_CEED GT TECH 2015
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11 Posts
Carbon deposits of any kind is a result of poor quality feul, and poor quality engine oil, but mostly feul! It is recommended that a feul with a cleaning agent included in it to be used, any other feul will diminish the performance of your car drastically (iv tested this in 2 kia models that had specific feul recommended for them) BP ultimate in Australia is recommended, so 1 day I decided I'd put in 95 a full tank just to test it out, I burned the ultimate in the line (5km) after that my acceleration began slack, cars I could thrash off the mark easily gave me a whopping easily.. Point is, poor quality feul burn fast an burn dirty this is a proven fact, BP ultimate is expensive but it gives me 760km per tank, BP 95 Is a little cheaper but gives 640km per tank. BP ULTIMATE cleans my engine, BP 95 does not in fact its a dirty feul, not as bad as BP 91 but non the less dirty... Choose your feul wisely it determines the life an performance of your engine.. I'v tested this in my Kia pro ceed gt tech 2015 and a kia cerato 2.0 2016.

Sent from my MHA-L09 using Tapatalk
 

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2016 Sorento
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Theres no way of getting around positive crankcase fumes needing to be reintroduced into the intake, toyota and Ford have designed a dual injection system where they combined port injection with direct injection and that gets rid of the problem but now you have more parts that can fail.
but you can install a catch can, and every 30K run sea foam into the throttle body and burn off any carbon build up, also valvoline just came out with an oil that aids in eliminating carbon build up in intake valves called modern engine oil.
I personally like the catch can idea and cleaning the valves with sea foam every 30k, that sould solve that issue altogether.
 

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2017 Kia Sorento SX, 2004 Grand Prix GTP w/mods
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GDI Carbon Buildup - 2017 models?

Theres no way of getting around positive crankcase fumes needing to be reintroduced into the intake, toyota and Ford have designed a dual injection system where they combined port injection with direct injection and that gets rid of the problem but now you have more parts that can fail.
but you can install a catch can, and every 30K run sea foam into the throttle body and burn off any carbon build up, also valvoline just came out with an oil that aids in eliminating carbon build up in intake valves called modern engine oil.
I personally like the catch can idea and cleaning the valves with sea foam every 30k, that sould solve that issue altogether.
I agree with this 100% and have used CRC intake valve and turbo and plan to install a catch can. I mean let's face it, doing all you can to keep blow by oil from passing over the valves regardless of injection method, just makes good sense.
 

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2020 Sportage "GT Premium" (1.6-liter turbo w/7-speed DCT)
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They have designed the engine to inject fuel in such a way that it does in fact get some onto the backside of the valves so major buildup doesn't get a chance to accumulate. This is a common technique on the more recent engine designs and is used by several different companies, This is what has been determined to work best to reduce the deposits. This method is done by injecting fuel during the cycle where the valve is in the open position so that a mist of fuel / air does get exposed to the valves while they are open. While not as good as fuel coming down into the chamber through the valve, the exposure is enough to resolve the problem.
Seriously? The claim is made here that air turbulence in the cylinder is SO extreme that atomized fuel (misted into the cylinder) is blown up past the intake valves, past the incoming blast of air, to dampen the back side of the intake valves with a little fuel and thus clean away carbon deposits? I refuse to believe without evidence that anything of the sort happens at much above idle but it's still hard to believe that such magic could happen even in an idling engine. What you describe has little to do with "injecting fuel in such a way" but rather with air swirl in the combustion chamber at idle being SO extreme that air/fuel from the cylinder is carried across the back of the slightly open intake valves. Moreover, all this magic in defiance of physics happens without anything unusual-looking in the intake, and without any patents or any advertising claims that you can site. We should just take your word for it? Wow.

Mazda's Skyactiv-G engines are claimed (by Mazda themselves) to use high heat levels routed to the intake valves to burn away GDI carbon deposits. Despite their sophisticated engineering, they weren't able to figure out how to get fuel mixture to magically fly out of the cylinder and upstream into the intake tracts the distance necessary to do what you've described (or imagined).

If you have any patents or advertising claims that you can refer us to, then I'll be happy to eat my hat in public.
 

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2018 Sorento LX V6 AWD Conv. Pkg. Tech Pkg.
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182 Posts
I was at the local Kia dealer here in Santa Fe last week, and I asked the service manager about the GDI carbon build up issue, and he told me that it is not an issue, and he has never seen a problem with it even at high mileage with the current Kia engines.

Note that I take everything I hear at the dealer with a very big grain of salt, and am just reporting what he said.
 

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I've noticed carbon build up on tops of my cylinders. 2016 Sorento only has 87,000 miles on it. I also noticed the oil seems diluted with fuel after an oil change at about 1,500-2,000 miles.
I'm gonna start running a potent fuel additive concoction (like 6 bottles of techron in a half tank of premium ethonal free unleaded) right before every oil change to see if this cleans up the carbon. I'm also gonna do oil changes with half 10w-30 to half 15w-40 on oil changes, or perhaps full 10w-40, to help keep the oil thicker, longer.

Scotty Kilmer says GDI is not good in most car designs.
 

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Well, my 2012 Kia Sorento started consuming oil round 116,000 miles, did another oil change and tracked it, down 1 1/2 quarts after 3 weeks (about 1000 miles), added oil, had to repeat the process in 3 weeks. Brought it to the service center since I have an extended warranty, they did an oil change we are now at 121000, same process after about 1000 miles 1 1/2 quarts down. They open a case with the extended warranty company, long story short, the warranty company wanted them to strip down the engine to find the problem, they are blaming it on excessive carbon on the pistons, causing the oil control ring to lock down on the piston, allowing oil to pass through. Since in their opinion it is not a part failure, it is not covered under warranty. I'm looking at over 1,000 for the repair, they have to put my engine back together so I'm kinda stuck.
 

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I've never met an extended warranty worth it's ink. Always a loophole for them to skate through.

Sorry brother that sucks. Maybe if you run 3-4 super strong tank fulls dosages of different fuel cleaners with the best non-ethanol premium you can find through it it will clean enough off to stop the oil burn. Then just maintain every few months. By super strong i mean like a bottle of cleaner to each gallon of fuel.

I wonder if removing the spark plugs and soaking the tops of pistons down with a can of breakfree type sprays like wd-40 might soften the carbon and make it burn off easier with the fuel cleaners working with it? I have an outdoor wood boiler and when I have problem passages that won't get clean I soak those with WD-40 (or any of the brands) while it's cool, let it soak for a a day, sometimes I re-spray it and let it soak again and then right before I fire it up. Always gets the passages clean....
 

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2019 KIA Sorento SX 3.3L GDi V6 - AWD
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I've noticed carbon build up on tops of my cylinders.
The subject of the thread is about carbon build-up on the back of the intake valves - not on top of the cylinders.

I also noticed the oil seems diluted with fuel after an oil change at about 1,500-2,000 miles.
What made you come to that conclusion? Did your oil level go up? Can you smell gasoline in the oil? You say that the oil seems diluted with fuel. The only sure way to determine the presence and concentration of fuel in the oil is to have an oil analysis done.

I'm gonna start running a potent fuel additive concoction (like 6 bottles of techron in a half tank of premium ethonal free unleaded) right before every oil change to see if this cleans up the carbon.
First off, the reason for this carbon build-up in a KIA GDi engine is that the back of the intake valves are not washed with fuel (since the fuel is sprayed directly in the combustion chambers). Therefore, adding a fuel system cleaner to the gas tank - irregardless of the potency - is going to do very little in cleaning this carbon.

Second, adding 6 bottles of Techron to half a tank of gas (and before every oil change?) is just crazy!!! This is serious overkill and can do a lot more harm than good.

I'm also gonna do oil changes with half 10w-30 to half 15w-40 on oil changes, or perhaps full 10w-40, to help keep the oil thicker, longer.
A 10W-40 oil (or any 40 weight oil) is thicker than needed (even for where you live) and will not keep the oil "thicker, longer". And also will do nothing to mitigate your carbon issue. Just stick to a high quality 5W-30 oil (preferably full synthetic) with a SN Plus rating.

Kilmer says GDI is not good in most car designs.
Scotty Kilmer's opinions are highly overrated.

Richard
 

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2019 KIA Sorento SX 3.3L GDi V6 - AWD
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P.S. I forgot to say: Welcome to the Forums!

😉
 

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I've done oil changes for 30 years. I've observed running thicker oils stay thicker when mixed with fuel or run for longer times.

Running thicker weight oil and doing those flushes have never hurt any of my dozens of used vehicles thus far. I've never bought a brand new car and get high miles (240k +) out of them before selling for the same price or more than I paid for them. Plus my liability only insurance is low, low, low compared to collision/comp. I've also done intake spray cleaners with the fuel additives.

I just read thread is about excess carbon anywhere. I'm sure it's on the valves also.

I'm finding it hard to believe that any maker that uses plastic intakes, valve covers, cooling control housings and the like, directly on the heads are well thought out. Where's the plastic motor? Oh it melted! Lol

Like I said all the fasteners were marked with OEM paint and all were almost loose. Barely snug. Plastic dumb thing to use on hot motors.
 

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2019 KIA Sorento SX 3.3L GDi V6 - AWD
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...running thicker oils stay thicker when mixed with fuel or run for longer times.
Yes, I understand what you're saying (and thank's for clarifying). Obviously a 40 weight oil will always be "thicker" than a 30 weight oil (it's viscosity at operating temps will be higher). It will be thicker when you pour it in your engine, and, all things being equal, it will still be thicker when you drain it. That goes without saying.

But that's not what I was objecting to. My comment was in regards to the "longer" part of your "thicker, longer" statement. The point I was trying to make is that, if your motor oil is being diluted with fuel, it will "thin out" at the same rate whether you're running a 30 weight oil or a 40 weight. In other words, running a thicker oil is not going to have any affect on how fast your oil is being diluted. That's all I was trying to say.

Yes one of the main reasons that some people choose to run a motor oil of a "higher viscosity than recommended" in these GDi engines is to mitigate oil thinning due to potential fuel dilution of the oil. However, you first have to find out if fuel dilution is in fact an issue in your particular engine - it might not be.

The only sure way to find out if your engine has a fuel dilution problem is to have an Oil Analysis done on your oil. You can check out my Oil Analysis (and comments) HERE. Fuel dilution of the motor oil was not a problem in my case.

Now if it is determined that your engine does have a fuel dilution problem, then you can consider going up a grade to mitigate the issue. Of course it does depend on how much fuel is in the oil and if the oil has in fact thinned out-of-grade. When the fuel dilution is only at minor to moderate levels what some people will do is choose an oil that is at the upper end of the recommended oil's viscosity range or one that is at the lower end of the range of the next oil grade up (e.g. a thick 30 weight or a thin 40 weight).

You have to consider that if you start off with a thicker-than-necessary oil and your fuel dilution is only at a minor level, that oil will most likely still be thicker-than-necessary when you drain it.

Hope that makes sense.

Richard
 
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