Possible Fuel Oil SOLUTION To Dilution.

  1. retuks

    retuks Member

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    The first thing that came to mind after reading this forums' and the webs' countless threads of woe and uncertainty was the simple question of "wouldn't you be able to just vent it off while the car isn't running?" So I have taken a scientific approach to deal with the inherent fuel oil dilution in my spare time at my workshop.

    What I have found is rooted partly in common sense but also comes with it's own headaches if practiced by owners of this vehicle; pulling out the dipstick an inch or 2 - just enough to expose the sump to air outside - and removing the oil cap after a drive. The latter isn't necessary but it's another way fuel could evaporate off oil that's already mixed in and distributed through the head side of the engine immediately after operation while it's nice and hot and the opening is a lot wider than the dipstick channel.

    To test this theory, I took 3 bottles. Filled the first to 1/3 liter of 0w-20, marked it's level on a flat surface, then poured 1/3rd of that amount of 92 octane into the oil, mixed it up and took a measurement of the new higher oil level and set the clock at 1220 when i did so and let it sit with the cap off. For a control subject to test how well fuel evaporates at all on it's own, I took another bottle and filled with 1/3 liter of just 92 octane, marked, timed and let that sit with it's lid off in tandem to the diluted oil to monitor both rates of evaporation over an 8 hour period. The last bottle i filled with 1/3 liter of pure 0w-20 and did the same procedure just to be sure oil couldn't evaporate on it's own either. All bottles were tested indoors with plenty of ventilation between 72-76 degrees F. relative humidity 85%.

    After the 8 hour period, I could clearly see the fuel bottle 3mm below it's original line. definitely evaporating at a decent rate. The diluted oil wasn't evaporating as quickly at nearly 2mm below the marked line, but nonetheless it was definitely decreasing as the fuel separated from the oil and vaporized out of the bottle. The pure oil bottle did not stray from it's mark at all just as suspected.

    This in practice has a user error risk to it - forgetting to seal your dipstick and oil caps before setting off each morning, or critters getting inside if you live in a wildlife infested area. But for the competent individual who doesn't mind adding a (albeit unnecessary) ritual to their daily routine after going to and coming home from work and parking your car for long periods of time, this could be a viable way to combat the dilution problem until honda can find a more permanent fix.
     
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  2. Design

    Design Senior Member

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    Interesting observations. Thanks for sharing. :cool:

    IMHO, it's more practical to drive a few extra miles at operating temps every so often, vs. subjecting the crankcase to additional contaminant risks. The lean burn should be more than sufficient to burn off excess water and fuel. At least, that's been my experience.

    For the record, dilution is a known (and manageable) side effect of all TCDI powertrains. Though Honda admittedly has a few that fall outside the operating spectrum due to a "perfect storm" of short trips, cold ambient temps, and the inability for the motor to reach operating temps quickly.
     
  3. calonzo

    calonzo Senior Member

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    And they have issued a recall for an engine software update (at least on my 2016 Touring) to address the issue.
     
  4. hobby-man

    hobby-man Senior Member

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    What vessel did you conduct this experiment in? I ask because the surface area of the exposed liquid will greatly affect the rate of evaporation.

    The gas and oil in the engine will be sitting in the pan, which is a long way from the outlet at the oil cap/dipstick. The air above the surface will quickly become saturated with gasoline vapour as it begins to evaporate and you are then rate-limited as to how quickly it mixes and equilibrates with ambient air at the oil cap.
     
  5. saiko21

    saiko21 Senior Member

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    Nice little experiment. The only problem with your conclusion is that you performed the experiment indoor with higher temperature and humidity which is not true as the car would be sitting outside. The temperature varies from morning to night and the oil pan sits below the engine. As @hobby-man mentioned the oil cap is long way from the pan. I guess the only way to avoid gas in oil ( assuming you are doing lot of short trips) is run on highway for 5-10 miles or try to drive at >75mph for few miles. That should take care of the problem if the Honda software update didn't fix it for you. GDI is prone to little oil dilution and you can't avoid it.
     
  6. OP
    retuks

    retuks Member

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    It's always good to challenge data and ask questions, just as I have done - which is why I did the experiment in the first place. I realise that these tests have their flaws and the environment I conduct it all in will greatly change my results and won't determine whether said results will apply to everyone in other areas of the world.

    I used 2 liter water bottles. You definitely have a point in regards to the vapor, as I have left the bottle that had diluted oil sitting in it's same spot in my shop until this point and it seems to have slowed a bit, but it has not stopped evaporating even with such a small opening as far away from the surface of the oil as it has. The viability of this method will fall on the question of whether or not the rate of evaporation will be greater than the fuel added to the pan between trips. So maybe not a solution for someone taking short trips on a day to day basis, but someone who might be gone for an extended period of time from their car might be able to realise some benefit. This is an experiment that can be conducted on ones' own in a realistic setting; simply trying it on your own car as it sits and check your oil level before and after.
     
  7. OP
    retuks

    retuks Member

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    #7 retuks, May 18, 2019
    Last edited: May 18, 2019
    Thanks. Above all else, I did it for fun. I understand that indoor and outdoor temperatures vary. I also live in a tropical climate that never sees extreme temperature fluctuations (average 65 - 85 F all year long. 75-80 F 90% of the year). However, when I said "indoors" I meant my shop, which is actually a giant open garage with 9 ft x 35 ft openings on both ends. A small breeze blows through it and I mainly used it to keep my bottles out of the sun. For me, sitting outside in 75 degree weather would mean engine bay temps of 75 degrees or greater. Even so, my car sits in a garage.

    In regards to the oil cap being a long way from the pan, this is why I said it wouldn't be necessary without having just stopped from driving, while there is a good amount of oil still simmering throughout the headwork where one could benefit from using the wider opening to allow hot vapor to escape while the oil (and fuel mixed in) is still up there.

    I own a sport hatch 6 speed manufactured mid 2018 and I still noticed oil building in the pan despite driving far and quickly. Driving further and faster should mean more fuel is removed from the oil as I check the stick, but this isn't happening. I have no recall out for my vehicle, and they won't update my software for free. Like most others, I am just doing what I can and trying what I can try. I am fully aware that no part of my experiment - nor it's practices - is in any way an exercise in practicality or convenience. As a car designed to be the epitome of a daily driver, I really wouldn't have thought I'd be trying to perform rituals on it. (I am all too familiar with rituals in my other vehicles. :rofl:)
     
  8. saiko21

    saiko21 Senior Member

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    @retuks if you complain about the gas smell in the oil. The dealer would check and perform the software update if required. I hope my 2019 Si is with new software from factory and yet I get little gas smell when i check the dipstick
     
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  9. Micah

    Micah Senior Member

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    Boy howdy that is a lot of effort and investigation. Good to add it to the forum for posterity. Personally I feel taking long drives on the highway and performing IOA with Blackstone is a better use of time and money, but your testing certainly has merits. In NJ where I live though it wouldn't be practical with the humidity, squirrels, chipmunks, mice, moles, cats, insects, and pollen. I suppose if you had some type of sealed and controlled environment garage, your method would be great. But I am gonna go out on a limb here and say the venn diagram of civic owners wouldn't have much overlap.
     
  10. Troy Jollimore

    Troy Jollimore Senior Member

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    Heh. ‘Far’ would be Honolulu to the North Shore, at least!
     
  11. civicls

    civicls Senior Member

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    Just change the dam oil more often, like 1000 miles earlier. Done.
     
  12. OP
    retuks

    retuks Member

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    And that's definitely not happening haha, that's a 2+ hour ordeal on an average day.



    A couple assumptions being made here. I don't adhere to the owners OCI. In fact, I do it every 3000 miles (the first one I waited to a little over 7000 before I caved), my work schedule and time windows simply don't support changing it every 10,000 miles, so changing it every 9 doesn't sound much better here. 3k many would say is overkill these days, certainly 2k would be. I have to adjust my changes to the lifestyle I live rather than trying to change my whole lifestyle for a 21,000 dollar daily driver. By comparison, I have to change oil in my flex fuel vehicle every 1500 miles running E85. 3000 if I exclusively use pump so it really isn't a problem of OCIs.
     
  13. OP
    retuks

    retuks Member

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    #13 retuks, May 23, 2019
    Last edited: May 23, 2019

    Thanks. I actually sent my oil sample (the one i did the experiment on) to blackstone for fun to see what they'd find (surely the results would appear catastrophic!) can't wait to see them. I'll also send one in 1500 miles from my vehicle. I'm close to my next oil change. Driving an mx5 at the moment though, won't be back in the civic until probably next week (too many cars.)

    The dealer here must be really lousy. They didn't offer anything when I tried this over the phone. maybe I'll show up in person and try again. If it's a simple tuning solution, I'd love to try. One thing I don't like about this car is having to choose between cold engine wear and sufficient fuel evaporation. Although my car does idle upwards of 2k rpm upon cold startup, it's done this since new and I'd assume it has to do with getting that temperature and oil lubricating the compressor as quickly as possible. It always had me a little concerned though as you can always hear what sounds like a very quiet knocking every time it does this (the sound has a likeness to bubbling up a hookah imo. PS i don't smoke haha). It goes away when warmed though.
     
  14. Gruber

    Gruber Senior Member

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    #14 Gruber, May 23, 2019
    Last edited: May 23, 2019
    That's the right approach - experimental. Experimenting is fun, but simulating is more useful (with a car instead of a bottle).

    Of course there is already a lot of basic knowledge in the area of fluid mixtures. The evaporation rate will always be proportional to the equilibrium vapor pressure of the light component (fuel), which in turn is proportional to the fraction of the light component in the mixture. You tested a 1/3 fuel 2/3 oil mixture, which will initially evaporate fast, then will significantly slow down as the fraction of gasoline decreases. 1/3 is a very high oil dilution case, rather alarming, so it doesn't apply to most cases. My oil dilution never exceeded the plastic dipstick tip, so it's less than 10%.

    The second issue is kinetic: the diffusion of vapor 1. through air in narrow openings, 2. through oil. It will be relatively slow through the dipstick tube compared to a 2L bottle. Then, if the oil is sitting still, the gasoline will evaporate faster at first from the surface and then evaporation will slow down as the gasoline has to diffuse through the oil before reaching surface.

    The next issue is that gasoline is a mixture. It has lighter and heavier components (such as ethanol and a lot of different hydrocarbons). The lighter components will evaporate first, relatively quickly, than it will slow down. Although even the heaviest fraction of gasoline is much lighter than the lightest fraction of the oil, the difference in evaporation rate will be significant. In addition, chemistry plays a role and some components of gasoline may have a great affinity to some components of the oil and will produce very low vapor pressure over oil mixtures and evaporate very slowly.

    Finally, the temperature rules here. Vapor pressure of any liquid increases exponentially with increasing temperature. Vapor pressure of fuel in oil will be many times greater at the engine operating temperature than at room temperature. For example the vapor pressure of pure iso-octane is 0.065 bar at a summer ambient temperature (77 F) but increases to 1.035 bar at water boiling temperature (212 F). That's 16 times. If the outside temperature is at water freezing, (32 F) the factor is about 60 times.

    So the real experiment would be to note the (long time cold engine) level of oil on the dipstick, then warm up the car and let it sit for a long time with 1. dipstick in, 2. dipstick out, and see the difference it made to cold oil levels. I expect no noticeable difference.
     
  15. civicls

    civicls Senior Member

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    So your saying you change it every 3k, but you don't? Do you change it every 10 or 3k?

    If you think 1500 miles or even 3k miles is a normal schedule for a modern car then I really don't know what to tell you...that is overkill
     
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