Mitigating Carbon Deposits on 2025 Honda Pilot with J35Y8 Engine

[Cujet]

Granted, this is the first J35 engine I've owned, but I've never seen anything like this before. I have HPL Premium Plus PCMO waiting in the wings, but I don't know if it contains Ans, or is just PAO.

I sent a sample this morning of the current oil to Wearcheck. With the holidays, I don't expect to hear back for a couple of weeks. At this point, I'm also trying to figure out why the Manganese level is 14-16ppm when the VOA shows zero. I'm hoping it's the fuel I was using and have not used during the 3k miles so far on this OCI.

The lower the pour point the more likely the oil is PAO. Conversely, AN's don't have a low pour point and may have a published pour point in the -30ºs to -40ºs range (may depend on PAO content). Also if you have a sensitive nose, AN's have a pungent odor and smell a bit like mild mothballs.

But any way you slice it, AN's are phenomenal with regard to high temp stability and clean filters over time.

 

[incognito_2u]

Years ago, Valvoline had an oil product called “Modern Engine” which claimed it reduced or eliminated IVD in GDI engines. Although they have long discontinued that product line, I wonder if that technology continues to exist in the Valvoline Restore and Protect? If so, this may be the way to go moving forward.

 

[KrisZ]

Not sure what fuel brand would have to do with engine oil carbon deposits. OP is barking a wrong tree focusing on the fuel.

How does OP know these were carbon deposits? This is a brand new vehicle, the last thing it should have is carbon deposits. These could be from breaking in guides, maybe bits of RTV?

I could not chase a solution yet, just change the oil at 5k intervals, which should be the max for a GDI engine anyways, and monitor that oil filter. It should clear up in an OCI or two if it’s from break in or the assembly process.

 

[rstsco]

Not sure what fuel brand would have to do with engine oil carbon deposits. OP is barking a wrong tree focusing on the fuel.

Not only am I wondering if the fuel is contributing to the carbon deposit in the oil filter (which I highly doubt, also), I'm seeing if the fuel used during this OCI is the source of the Manganese. I've run Shell premium several years from the same station in my Audi and nary a single ppm of Mn has ever showed in a used oil analysis.

How does OP know these were carbon deposits? This is a brand new vehicle, the last thing it should have is carbon deposits. These could be from breaking in guides, maybe bits of RTV?

These deposits seen here were not in the first OCI at 500 miles, and if there after another 4k miles, didn't really notice anything alarming. This OCI was 5.6k and has quite a bit of material in the filter media. Same filters were used on the two previous oil changes, so it's not related to having different media. The majority of the miles, 4k, my wife put on a whirlwind trip to Wisconsin, Canada, and back home.

I could not chase a solution yet, just change the oil at 5k intervals, which should be the max for a GDI engine anyways, and monitor that oil filter. It should clear up in an OCI or two if it’s from break in or the assembly process.

This isn't due to the break-in or assembly process, or I would have seen it in the first two OCIs, not just the last. Again, same oil, same filter.

I'm more convinced than ever what I'm seeing is due to the VCM system continuously switching the rear bank of cylinders off-and-on in Normal drive mode, confirmed using a scan tool and monitoring a couple of different parameters, one being the rocker arm oil control solenoid which controls the oil valve to the VCM system and the other showing the number of active cylinders, e.g. 6-3-6, etc. as seen on this graph.

I'm not going to wait and see what may or may not happen, but continue barking until I get to the correct tree. We've just started driving in either Tow or Sport drive modes, which I've confirmed in somewhat limited testing disables the VCM from activating. I've already sent an oil sample to Wearcheck to see if the Mn level dropped, so next step is to change the oil and filter, which has about 3k miles on them, cutting the filter open to see what it looks like. The next OCI will be Shell premium and only driving in Tow or Sport modes.

 

[KrisZ]

Ok, thanks for the other thread link. I think you are seeing soot in the oil and the filter. DI engines produce a lot of soot, similar to diesel engines, but the particles are much smaller and in lesser quantities than diesel engines.

There is likely nothing you can do about it. Perhaps fuel quality can have an effect, but I doubt it.
Cut the OCIs to 5k miles or shorter and don’t skip the oil filter change, if that’s what Honda recommends.

 

[GenSan]

Do you drive more spirited, sedated, a combo of both on a regular basis? OE
Oil filter I cut open on my 2025 Nissan Armada Pro-4x at 3,000 looked nothing like yours.

 

[dgunay]

There is nothing you can do about it - as long as it's top tier fuel that V6 engine runs happily with 87. Premium is just waste of money in this case. Octane rating has nothing to do with cleanliness.

Shorten OCI, avoid short tripping on a regular basis to minimize carbon buildup. You can always clean your intake ports when you're changing the timing belt at around 100k. You already have to disassemble half of the engine at 100k to change the belt, water pump etc. - might as well get that done at the same time.

 

[rstsco]

Do you drive more spirited, sedated, a combo of both on a regular basis?

I don't baby it, but have yet to track with it. My wife is excited now that I've asked her to use Tow or Sport drive modes. She only has to mash the selector one click forward to be in Sport mode and is enjoying the Pilot a lot more now, since her previous car was an Audi Q5 which could do 0-60mph in 5.5 seconds. The Pilot can't do that, but at least she feels like it's much more capable now.

 

[rstsco]

There is nothing you can do about it - as long as it's top tier fuel that V6 engine runs happily with 87. Premium is just waste of money in this case. Octane rating has nothing to do with cleanliness.

Until after the last oil change, I was running 87 octane from Quik Trip, which is Top Tier certified. I at least know, having used the Shell premium for the past several years, it doesn't contain Manganese. I'm also trying to find its source. Everything I've read on the J35Y8 engine, Manganese is not used in its construction. I didn't use any fuel systems' cleaners, so should have an answer to the Mn when I get the results from Wearcheck.

 

[GenSan]

If ever I get my first Honda it will surely be the Acura Integra Type S. LOVE that thing

 

[bdc101]

Hey @rstsco, not to bring this thread back from the dead, but can you tell me what kind of scan tool you are using for monitoring the VCM activation, and if you would recommend it? I am a new J35 owner (2020 MDX with J35Y5) and just trying to figure out how to take care of this Honda and what bidirectional scantool to use.

 

[rstsco]

Hey @rstsco, not to bring this thread back from the dead, but can you tell me what kind of scan tool you are using for monitoring the VCM activation, and if you would recommend it? I am a new J35 owner (2020 MDX with J35Y5) and just trying to figure out how to take care of this Honda and what bidirectional scantool to use.

I bought the XTOOL D8W and have only used it to view and record live data. It has many bi-directional functions for the Honda, but supports many other car brands. I feel I've already got my money's worth, having paid $531+tax the beginning of December 2025. Today's price is $699. At this price, I might seriously look at 10" models of brands including XTOOL and other brands.

One of the functions I needed was key programming. Our daughter's CR-V only has one key, and it's falling apart, barely held together with tape. I ordered two new keys which will be arriving tomorrow. They'll still need to be cut, but that cost is minimal compared to how much replacements from the dealer, and even the locksmith, would cost. I'll know this week how good this function works.

 

[PWMDMD]

Toyota uses port and direct injection. The non-US version of the 2022 Audi used MPI. Only the US version was GDI only.

US car companies are being run by none other than PT Barnum reincarnated, as we keep buying them.

I have one GDI engine but only because the whole package was very compelling (Forester). It's also sort of an experiment to see how much of an issue it really is and if I can mitigate it with oil selection and running a top end clearer every 5k miles. If I have to get one of four vehicles walnut blasted at some point, I can live with that. PFI or GDI/PFI is a major factor in whether or not I consider buying a vehicle and I'm much more likely to buy a Toyota/Lexus in the future over a Honda/Acura based on this issue alone.

 

[bdc101]

I bought the XTOOL D8W and have only used it to view and record live data. It has many bi-directional functions for the Honda, but supports many other car brands. I feel I've already got my money's worth, having paid $531+tax the beginning of December 2025. Today's price is $699. At this price, I might seriously look at 10" models of brands including XTOOL and other brands.

One of the functions I needed was key programming. Our daughter's CR-V only has one key, and it's falling apart, barely held together with tape. I ordered two new keys which will be arriving tomorrow. They'll still need to be cut, but that cost is minimal compared to how much replacements from the dealer, and even the locksmith, would cost. I'll know this week how good this function works.

$699 holy moley!