Carbon buildup on valves in GDI

S60doc

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Just waiting for the day somebody scopes their intake and posts some pics of how they look at 80-100k miles
I saw on instagram there is a guy who is mechanic only for hondas. I checked his profile i saw 7-8 CRV, Honda Fit which has 1.5T engines. One CRV was even 37k on it. But guy says they all buying cheap fuel. And their oil change usually over due. So I'm assuming as long as we change oil on time and we buy Premium fuel we should be good.



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due. So I'm assuming as long as we change oil on time and we buy Premium fuel we should be good.
quaity oil too.. stick with something that has high detergent in it.
 

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I saw on instagram there is a guy who is mechanic only for hondas. I checked his profile i saw 7-8 CRV, Honda Fit which has 1.5T engines. One CRV was even 37k on it. But guy says they all buying cheap fuel. And their oil change usually over due. So I'm assuming as long as we change oil on time and we buy Premium fuel we should be good.



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Of course CRV and Fit owners are gonna buy the cheapest 87 unleaded and Jiffy Lube oil change (3k miles overdue) they can find. They usually aren’t car enthusiasts.

And there are a lot of Si owners that aren’t enthusiasts that know any better either. This forum just makes it sound like everybody is because anyone who finds this forum are here because they care about their car.
 
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indiMjc

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Taking the lack of oem catch can as a sign that they're not beneficial seems a bit short sighted imo. You also have to think of why they might not want to put one in when determining if they're beneficial. The lack of oem catch cans doesn't really seem to prove anything. For one, they need to be checked on shorter intervals than, say, your oil needs to be changed. So putting one in from the factory means more service visits for someone who never pops their own hood. Also I don't even want to know what would happen if one filled all the way up and wasn't emptied. They're probably dangerous for the type that doesn't regularly check over their vehicle. There's even a titration phase (probably the wrong way to put that, it's a medical term) where you have to frequently check it to get an idea of how fast it fills up. Normal people just aren't going to do that.

Also this is all to ignore that the pcv system is for emissions, not performance or longevity. It prevents unburned fuel from escaping via the exhaust and instead pipes it back into the intake. If not for emissions standards, would we even have a pcv? I just hate the idea of stuff being sprayed into the intake on a sensitive motor.

There is a lot of people who say that carbon buildup isn't as big of a concern in these Honda motors but I can't find anyone that knows why and I'm a bit leery about that kind of thing. One even claimed that there were port injectors, hence me asking about it. I've worked on a lot of trucks with NA motors but just don't really know squat about these small displacement, forced induction motors they're putting in cars these days. If I ignore the Honda specific forums and look at general research into direct injection, all the papers I've seen seem to indicate that there's no negatives to a catch can and only potential positives.

I'm not trying to argue or claim that the information I found is gospel or anything. In fact I'm inclined to agree with a lot of what you guys said. I'm just providing the other side so we can discuss it fully. Just wanted to make sure I give that little disclaimer.

Reason for 5w-30 is that's what is recommended in Euro cars and lighter weight oil is ONLY used to give better fuel efficiency,
I read some peer reviewed research about the thin oil in direct injection motors and the claim they made wasn't about fuel efficiency. They claim that oil dilution is encouraged if the car is ran below operating temperature and that the thin oil lets the motor reach temperature faster. I'll see if I can find the literature but no guarantees lol, I've been reading a ton of stuff these last few weeks so idk if I'll be able to track it down.
 


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I also made a lot of searching about these engines.
-Don't buy regular fuel, I'm buying Premium. 3rd party companies says detergent percentage more in Premium fuel.
-Warm up your engine at least 10-15 minutes. Even summer times I'm doing it.
-Change your oil regularly. I mean when my oil life is %30-40 I go for oil change.
- yes I also checked everywhere our engines doesn't really need oil catch can.

I'm sure there is members on forum who has over 70-80k miles on their cars. So maybe they can reply better than me. My car has 43k.
All fine, except for warming up the engine for 10-15 minutes. I advise against it, and the reason is NOT anything related to fuel waste or pollution (which are both negligible).
 

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You should buy high octane fuel if your car requires it, like if you have a Type R or an Si.

You can buy high octane fuel if your car has a map for it, like a 1.5L Sport or Sport Touring.

If you put 93 into a LX or EX you are just setting money on fire. "premium," "detergents," and "top-tier gasoline" are all bullshit marketing terms that mean literally nothing.

Octane is a measurement of a fuel's ability to resist pre-detonation. Nothing more, nothing less.
The difference between "should" (allegedly for R and Si) and "can" (allegedly for Sport/Touring hatchbacks) was purely invented by.... you. ;) No support for this in Honda manuals. No Honda civicx requires premium fuel, in all cases it is "recommended." Btw. regular is also only "recommended," for the other models. :p

The hatchback manual does not specify here Type R or the 2.0T engine. It only "recommends" premium fuel for the "Models with the label "PREMIUM RECOMMENDED," which are the "sports" and the R.

Similarly, the sedan manual specifies the "Models with SPORT mode" (which means Si in this case) and recommends for them the premium fuel.

The wording in both cases is identical, so the premium is recommended equally for Type R, Si, and Sport/Touring hatchbacks. Any difference as in "should" and "can" is pulled out of.....
 

Gruber

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I would recommend Pennzoil Platinum. Keep with the recommended 0W-20. It has a high detergent/dispersant additive - higher than Mobile 1.
you will notice that it gets just a smidge darker quicker than some others, but that just is proof in the “pudding” that displays its ability to suspend carbon contaminates.
I doubt you can back up your claim that anything gets darker quicker than Mobil 1. Or even that Pennzoil has a bigger detergent load than Mobil 1 - how do you know this?

Oils get dark not only by dissolving anything but also just from exposure to engine hot spot temperatures. In any tests of this kind, and there are more then one or two out there, I've seen Mobil 1 oils get dark faster than other oils. Also, what might be surprising to some, some older conventional oils may resist thermal darkening the longest. This is because, what darkens thermally are some additives.
Telling apart the thermal darkening from dissolution darkening is rather impossible without lab tests.

 

Benster

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The difference between "should" (allegedly for R and Si) and "can" (allegedly for Sport/Touring hatchbacks) was purely invented by.... you. ;) No support for this in Honda manuals. No Honda civicx requires premium fuel, in all cases it is "recommended." Btw. regular is also only "recommended," for the other models. :p

The hatchback manual does not specify here Type R or the 2.0T engine. It only "recommends" premium fuel for the "Models with the label "PREMIUM RECOMMENDED," which are the "sports" and the R.

Similarly, the sedan manual specifies the "Models with SPORT mode" (which means Si in this case) and recommends for them the premium fuel.

The wording in both cases is identical, so the premium is recommended equally for Type R, Si, and Sport/Touring hatchbacks. Any difference as in "should" and "can" is pulled out of.....
Yes, these engines can run on regular, as someone stated, they will run like garbage, won't boost until 3500-4000rpms, will knock like crazy so you'll never get your advertised power rating, on top of most likely reduced longevity because of all the above. If a manufacturer says recommended, it means if you want the engine to drive properly and make it's power, you HAVE to run that grade. You'll be able to put regular in an SI if you get stranded and the only gas station in the area only has regular, but as stated above, it won't run right. Honda filled my brand new car with regular and it drove like shit all the way until the 2nd tank of premium and I did notice the difference, more responsiveness, more power and it revved faster too.

There is one thing that ''can'' be wrong though, and it's that using higher grade fuel if a car doesn't recommend or require it makes no difference. On turbo engines especially, and I also found on Chevy V8s for myself, the computer will adjust timing up to the point of detonation, increasing power, fuel economy, responsiveness, etc. I can't say if the non sport civics do it as I haven't tried it but multiple vehicles I owned, running premium made a difference even if they never asked for it. The other half I owned, premium didn't change a thing though so you'd have to try, 6-7 fuel tanks is where you'll start seeing a difference,

On the 1/2 ton truck my dad let me use for a few months, the truck went from not spinning tires from a stop to spinning to 70kph and went from 700km/tank to over 1000 just by running premium. That was around 2003 where the price difference in premium was only 6c/L so it was worth it. Today, with a 20c/L difference? Probably not so much.

Octane rating is not the fuel's ability to not pre-detonate, it's the speed at which the fuel ignites. Higher octane means the fuel burns slower, which allows you to run more timing, more boost, etc. Less detonation is the result of a slower, more controlled fuel burn. There are tests on this if you take the time to do your research.
 

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This is literally true because the Si and Type R ECUs are able to pull timing hard enough to compensate. It will run like dogshit and it will get terrible fuel economy and it will make horrible power, but it will run. None of what I posted above was me pulling things out of my ass, but here's me doing that: running low octane fuel in your Si or Type R is probably going to cause an incomplete burn and you are going to massively exacerbate the carbon buildup problem.
You are again making things up. What "incomplete burn"?
If there was "incomplete burn" the O2 sensors would see it as rich mixture and the PCM would adjust the fuel down. Do you see the AFR get low on regular? It can't, becuse that would violate emissions regulations. If Honda allowed running on fuel that results in unburned gas in the exhaust, that would be illegal.

But the point is that you assume that the Sport hatchbacks would not run regular at decreased power, or like "dogshit" if you prefer? Remember that what makes an engine require high octane is pressure, and that means the compression ratio and the boost. That's also what makes the extra power possible with high octane, not just simply adjusting the ignition advance. Also remember that the Si has a tad lower compression ratio than the regular 1.5T, and the R has even lower compression ratio, while they both have higher max boost pressures instead. As a result, they all can run on regular, but all run better on premium. I'm quite sure if Type R had the compression ratio of 10.6 with the boost it has, Honda would have to require premium fuel.

I never tried running on regular, so I don't know how close to dogshit it gets, but obviously that's exactly why Honda recommends premium for ALL these cases equally - to get the specified performance and to avoid knock even at extreme conditions.
 


S60doc

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All fine, except for warming up the engine for 10-15 minutes. I advise against it, and the reason is NOT anything related to fuel waste or pollution (which are both negligible).
Oh I'm waming up my engine because oil dilution issue. Maybe not necessary for summer season but I think warming up is necessary for winter season.
I commented couple times before, but I feel like I'm unlucky guy. I used to have 2007 Scion TC which has 2.4 liter toyota engine known for Oil consumption. I needed to add 1qt oil every 1000 miles. Then i got 2018 Honda Civic Sport MT. I was telling myself do a lot of searching this time before buying a car. Then I ended up with Honda 1.5T engine which known for Carbon buildup and oil dilution issues. I mean I haven't notice any symptoms for these common issues. But people talking.
I watched couple videos, surfed on couple forums. People saying that almost every newer car has problems. Because companies trying to make reliable cars with small engine/high performance and same time they need to meet emission standard.
I don't blame companies, they need to meet some standards. But Honda has been doing really good engines. And they don't even accept there is oil dilution issue :) anyway who is keeping their cars for a long long time.. . I'm planning to keep my car for a while. Let's see if there will be carbon build up issues lol.
 

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It requires a different fuel map to take full advantage of the extra octane. The 9 hp bump Sports have over LX and EX is because the Sport has a 91 fuel map while the LX and EX don't.

This is otherwise completely correct.
If this is right then we wouldn't have the fuel trims in the computer adjusting fuel delivery according to all the data it gets. The opposite would be true in that the sport wouldn't be running on regular or getting more power on the premium without requiring a custom tune. The computer is able and programmed to take every advantage possible from the octane in the fuel and SHOULD be making more power or keeping that same power with more octane. Example is when I was running 94 vs now 91, I never saw the kcontrol go over .54 even when revving past 6k. With 91, revving past 5500 almost instantly bring it between .59 to .69. That's only 3 points of octane and you feel the power loss pretty good. So yes, engines are able to make more power with the same maps on different octane fuels. For going beyond the safe tunes in the stock car or even the base maps from ktuner, a tune will be beneficial for sure.

But let's take this on a new thread if people are interested.
 

Gruber

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Oh I'm waming up my engine because oil dilution issue. Maybe not necessary for summer season but I think warming up is necessary for winter season.
I commented couple times before, but I feel like I'm unlucky guy. I used to have 2007 Scion TC which has 2.4 liter toyota engine known for Oil consumption. I needed to add 1qt oil every 1000 miles. Then i got 2018 Honda Civic Sport MT. I was telling myself do a lot of searching this time before buying a car. Then I ended up with Honda 1.5T engine which known for Carbon buildup and oil dilution issues. I mean I haven't notice any symptoms for these common issues. But people talking.
I watched couple videos, surfed on couple forums. People saying that almost every newer car has problems. Because companies trying to make reliable cars with small engine/high performance and same time they need to meet emission standard.
I don't blame companies, they need to meet some standards. But Honda has been doing really good engines. And they don't even accept there is oil dilution issue :) anyway who is keeping their cars for a long long time.. . I'm planning to keep my car for a while. Let's see if there will be carbon build up issues lol.
Well, Honda admits there is fuel dilution, they just don't admit it's an issue.....:dunno::) So I definitely see fuel dilution but I don't have an issue with it if it doesn't increase. On the other hand, any carbon buidup is only a threat at this time, but I would have an issue if it appeared..

The problem with longer "warming up" is that it is not necessary in the summer, and it doesn't work with the 1.5T in the winter. As a result of long "warming up" the car will actually run cool for a longer time and dump more fuel in the oil. This engine is not capable of warming itself up in freezing weather by idling. So I warm it up for a couple minutes max required until the ECT goes over a covid-19 patient body temperature, and then drive.
 

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Adding to this, No the L15 with DI will not have carbon build up on the intake valves like VW and other experience. Our engines actually spray fuel on the valve under certain conditions to prevent this. Honda has a cool animation of how this works here:
 

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Adding to this, No the L15 with DI will not have carbon build up on the intake valves like VW and other experience. Our engines actually spray fuel on the valve under certain conditions to prevent this. Honda has a cool animation of how this works here:
Good to see this video. I had previously heard under high revs the engine would do this, but I was never able to find the evidence to back it up.
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