Oil Dilution in non DI

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Dec 24, 2021
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I got a bit of confusion going on here, I originally joined these forums because I was worried about fuel diluting my oil. My vehicle is a 2018 honda clarity plug in.

So I do a lot of driving on electric, and now recently have been mixing it up with hybrid mode to prolong my battery in highway conditions.

I was about to install a catch can on my vehicle to help solve this problem because I believed my vehicle was DI.

So I went to honda to see how many pvc lines there are and the guy asked me why does it matter, and I told him the issue. He told me my vehicle is not direct inject it's actually MFI. That the gas is being sprayed into the intake and onto the valves, which is great. Is this accurate?

However, I noticed the first time I did my oil change on my car the oil smelled like a lot of gas was present, I realize this means nothing without testing the oil. However, I own 3 other cars and I do all my oil changes myself. I have never experienced this before. How is it possible that my oil is having any dilution when the motor isn't even direct injection? I will be saving a sample and sending it in for analysis, however since I changed my oil last I doubt the engine has even had 1500 miles driven on it of the 6000. The vehicle is primarily driven in EV mode.

My other vehicle an acura is MFI as well, and I do not smell gas when I do changes on its oil. Is there any other reason a brand new car would have dilution? I bought the car used from honda with 22,000 miles on it and now I am at 28
 
In 50 years, I've never not had some smell of fuel in my oil when doing an oil change interval(OCI). Some more than others depending on how much city/stop & go driving I've been doing. Especially with older vehicles. However I must say that with modern vehicles it is much less. And man, those old carb'd engines really stunk! o_O
 
25%? It’ difficult to say, I really don’ know. :rolleyes:

Yeah, some(fuel dilution) can be that strong smelling especially during the heat of summer in which the stench can really hit you in the face. 🤪
 
1500 miles out of 6000 is only 25%, wouldn't that be the same as short tripping?

@CharBaby my TBI is the same, when I pull the air filter to check it it about knocks me out with the smell of fuel, however my mech says it's not that bad and typical for TBI.
This^^^^^^^^^^^. Repeated cold starting of the ice. I get dilution in my Camry MPI. It's alot about the short drives in my case.
 
I was about to install a catch can on my vehicle to help solve this problem
Fuel dilution has been around since the days of carburetors, and a catch can won't solve anything on a street car.

 
In 50 years, I've never not had some smell of fuel in my oil when doing an oil change interval(OCI). Some more than others depending on how much city/stop & go driving I've been doing. Especially with older vehicles. However I must say that with modern vehicles it is much less. And man, those old carb'd engines really stunk! o_O
Never dealt with a carb engine, my first car I learned how to self care for was a 1999 honda accord. Kept that engine spotless, oil would go in almost the way it would come out and I would beat the living daylights out of that car.

Since I started driving, and since my parents do the same, I always put chevron 91 in my cars. That's the highest octane we have here in cali.

I got really no clue what the situation was or is, but I bought my car from the dealer as a CPO. It stated in the service section that an oil change was completed and all that. I did an oil change at about 1000 miles after purchase, probably 300 of those miles were driven on the engine. When I did an oil change the oil came out kind of dirty. It was very see through, and it had a strange tint to it. I usually dont get out from under the car when I do my oil change and honestly I smelled a lot of fuel.

May sound crazy, but I like the smell of engine oil. Not that I would wear it as cologne, but it has a distinct smell. It just smelled like a lot of gas.

So either they never changed the oil, and this was some really old used up oil or basically 300 miles of driving probably got this real oil real nasty which is fairly insane.
 
1500 miles out of 6000 is only 25%, wouldn't that be the same as short tripping?

@CharBaby my TBI is the same, when I pull the air filter to check it it about knocks me out with the smell of fuel, however my mech says it's not that bad and typical for TBI.
It's not short tripping. The car functions strange, I do not like for the engine to turn on when it's completely cold. So I when I leave my house I basically put the car in hybrid mode and let the engine turn on and let it warm up for 2 mins.

When my battery is fully charged it always keeps going back to EV driving cause the battery is really full. So the only way to keep the engine on is basically keep on hitting high revs on street driving. When I hit the freeway the engine will stay on in hybrid mode. That's about the only time I am getting full engine operation. But as stated the car is being warmed up.

No clue if this atkinson cycle engine has anything to do with it or not.
 
25%? It’ difficult to say, I really don’ know. :rolleyes:

Yeah, some(fuel dilution) can be that strong smelling especially during the heat of summer in which the stench can really hit you in the face. 🤪
It's not really summer yet. I would be so shocked if the vehicle smelled like gas with a lot of driving when the motor is in operation. However I charge at home, and I charge when I get to work. My battery is always full and I am driving on electric predominantly.

So that's why I am kind of surprised why there's any dilution when the engine is running so little. Again this is an assumption just simply made by the smell. Cant say how bad it is, but in my experience I have never had that much of smell and the last time I did my oil change it was like 60 degrees outside.

I am doing everything possible to keep the engine warm in case it is engaged.

Also on another note, fuel consumption wise. I have a full tank last me about 5 weeks. The tank capacity is 7 gallons. So basically since my last oil change until now I have used roughly 35 gallons of gas. Generally speaking, and depending on the car, some people will go through that in 2 weeks of driving in a regular engine.

I drove 45 miles today and used 2.5 gallons of gas on my acura lol
 
This^^^^^^^^^^^. Repeated cold starting of the ice. I get dilution in my Camry MPI. It's alot about the short drives in my case.
I understand with short trips, but honestly I am driving about 15 miles one way. Engine is being turned on at the start to get it warm, then I go on my way. After that yes it is mostly EV mode, so the engine is not on, but does turn on occasionally. Maybe all that adds up to short trip motor driving.

After work I usually get in about 30 miles of driving. It's a mix of 60% freeway and 40% street, and on the free the engine is rolling the entire time.

@circuitsmith Well it has been shown to provide some longer carbon build up time for DI engines. However I do not really need that, since my car isn't direct injection. The valves should be clean or have very light build up. Once I am using chevron which is all I use it will start to clean or stop any additional deposits from forming.

We will find out for certain this time when I do an oil change and see how everything looks and smells. I use the same oil on all my cars and I would hope now that direct injection is out of the way it will all be similar. Just that first time got me really tripped on this whole thing
 
First off, fuel dilution can happen with any type of fuel delivery mechanism, be it a carburetor, TBI, EFI, SEFI or DI. It is most prevalent on carbureted applications, because they lack the ability to fine-tune enrichment, and on TGDI applications because of excessive enrichment to control knock and the fact that the direct injection charge puts a lot of fuel on the cylinder walls, where, when it is cool, condenses and works its way into the oil pan.

But, high performance port injected engines can also suffer from fuel dilution, due to richer tunes and higher compression ratios, as well as on more pedestrian engines if they are not regularly brought up to operating temperature, which results in more of the operating profile taking place in conjunction with startup enrichment and cold cylinders/pistons/rings which seal more poorly and results in more fuel making its way into the pan.

Hybrids, that intermittently run the ICE fall into the latter camp with periods of short operation with poorer ring seal and excessive startup enrichment. Of course you can take solace in the fact that it would likely be even worse if it was GDI, lol.

If you want to know how bad it is, send a sample off to OAI/Polaris and have it checked.
 
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