Fuel dilution causes

[Danh]

A recent UOA from Polaris Labs on my 2015 Honda CRV showed fuel dilution of 5%, or in the panic range. This was after 2,700 miles of mostly highway driving in warm weather using Mobil1 AFE 0w-20. A 400 mile highway trip was completed just a few days before the sample and no short tripping occurred during this interval.

My Honda dealer, which had evidently never seen a UOA before, didn't know what to make of the report but ran a bunch of tests and found nothing. District tech support said in the absence of an actual symptom, no further testing was warranted.

I asked specifically if the dealer had performed a fuel injector leak-down test to see if an injector was leaking after engine shut down. The answer seems to be "no" as the dealer contends any such malfunction would be accompanied by a malfunction or computer evidence of a problem. Does this seem right to anyone? Or would a leaking injector repressurize quickly an not result in a driveability/CEL issue?

And if not a leaking injector, where could this quantity of fuel come from given the low mileage and favorable driving conditions? Lab error is a possibility I suppose, but Polaris says they double checked based on the level. As gasoline and oil stay together when mixed, the fact that it was sampled through the dipstick tube using Polaris equipment shouldn't matter, should it?

There's a temptation to ignore the whole issue (which the dealer surely expects me to do), just drive the car, be happy and forget about future UOAs. But this is BITOG...

Thanks for any thoughts.

 

[FordBroncoVWJeta]

How many miles on the CRV? We have a 15 CRV too, the people at my dealership is next to clueless....

 

[TwoWheelRider]

We have the same year and model with the fuel dilution problem. The dipstick smells like the gas tank. Getting tired of this Honda. First the vibration issue, now this...

 

[Ram01]

Fuel dilution causes timing chain wear . I would step up to a 5w30 syn oil .

 

[mclasser]

Interesting post. I'm eager to hear the responses on this.

 

[abycat]

in an older vehicle I would take the sparkplugs out and leave the key at the on position for an hour or two, with a battery charger on it and crank it over. But I'm sure your crv is a chore to do that. my coworker has an 01 Dodge minivan and last oil change he did the mechanic said he had two litres of fuel in the oil pan. The thing has 200k kilometers on it and runs like a top. engine has never been opened. He short trips the heck out of it and has done so since he bought it new. I think 5% and under is not really a big deal.

 

[Robenstein]

If the vehicle is direct injected, that can lead to higher fuel numbers in the oil. Years back when DI first starting popping up with frequency, it was discussed that North American fuel maps tend to be slightly richer than in some other nations due to emissions, and that was part of the problem.

I would contact the general manager of the dealership and express your concerns. If that fails, go above his head. Most dealerships are part of some owernship group. If that is the case with yours, I would contact them and Honda USA. You can also go on places like Yelp and Dealer Rater and let your dissatisfaction be known. When I was a Ford salesman, a former customer left a very angry review on Dealer Rater due to a service issue. The general manager called in everyone from service and just chewed butts to no end.

Squeaky wheels get the grease.

 

[Danh]

Originally Posted By: FordBroncoVWJeta
How many miles on the CRV? We have a 15 CRV too, the people at my dealership is next to clueless....


About 12,000. The fuel dilution issue is too bad because the car is really good otherwise. I brought up the viscosity issue with the service dept as well, but then I realized they had no clue what I was talking about or how fuel dilution and viscosity could be related. He told me to "...take it up with Mobil.".

Seems typical of service departments: if you come in for an oil change or a car that won't go, they are capable; thIngs in-between are are iffy.

 

[Danh]

Originally Posted By: TwoWheelRider
We have the same year and model with the fuel dilution problem. The dipstick smells like the gas tank. Getting tired of this Honda. First the vibration issue, now this...


We had the vibration issue too, but Honda's fix worked well for us. But Honda's fix for this problem involved a fuel economy compromise and I wonder if they became aggressive in reprogramming the PCM to recover some of the loss. This could involve runnIng lower revs, which could lead to pre-ignition, which could lead to over-fueling in some circumstances (and corporate denial). But who knows? Honda's flag isn't flying high at a our house, either.

 

[wemay]

Where GDI is concerned, fuel dilution has historically been worse the newer the car is, going away or showing trace amounts as you pile on the miles. At 12,000 miles i wouldn't worry about it and conduct a few more UOA to see if there's a trend. I don't know how useful a UOA can be with less than 20,000 miles on the ODO though.

 

[Falken]

There are a lot of factors for fuel in the oil.

But the mechanical ones that are controllable within reason on a newer car is just what you were pushing for, they need to do a proper leak-down test.

This is a SUPER simple test. If they are resisting doing it it shows they don't know very much at the dealership.

You can have a leaky injector that won't throw a misfire code when the car is running, but when the car is sitting there with the car off the rail will have pressure for a good long time allowing fuel to dribble every shutoff until the fuel dilution builds up.

The other reasons would throw codes generally, like if one cylinder isn't getting a proper spark a misfire code would pop up etc...

Short tripping in the Winter can add to the problem, as the car runs extra rich to fire up, allowing fuel to slip past the rings on a cold start. If you don't drive it until it gets nice an hot the fuel builds in the oil, but this is an extreme case and most just change the oil more often if they know they are short tripping in subzero weather.

In the mean time, you can run a bottle of Gumout or Regane and hope it allows the injector to clean up a bit so it stops leaking.

Push for the leak down test and even go somewhere else. Fuel dilution as mentioned really beats up your timing chain, it is something that should be fixed asap.

You can even buy a gauge yourself and look online (Youtube vids etc.) how to hook it up to your fuel rail and diagnose it, would probably be cheaper than paying for a mechanic to do the test.

I wouldn't pay more than 75$ to have this test done, it is really mechanics 101 stuff. Good job on your suspicions I fully agree.

 

[Rand]

If you are concerned with fuel dilution just step up to a 0w30 or 5w30

they are 15-25% thicker and will help with the oil thinning due to fuel dilution.

 

[SrDriver]

Originally Posted By: Rand
If you are concerned with fuel dilution just step up to a 0w30 or 5w30

they are 15-25% thicker and will help with the oil thinning due to fuel dilution.


That and change the oil more frequently along with testing.

 

[Danh]

Originally Posted By: Rand
If you are concerned with fuel dilution just step up to a 0w30 or 5w30

they are 15-25% thicker and will help with the oil thinning due to fuel dilution.
t

I have considered this, but then there's the warranty. If my dealer won't be my advocate in pushing this fuel dilution issue with Honda I doubt they'd help with a warranty claim if I was using a non-spec'd viscosity.

 

[Danh]

Originally Posted By: SrDriver
Originally Posted By: Rand
If you are concerned with fuel dilution just step up to a 0w30 or 5w30

they are 15-25% thicker and will help with the oil thinning due to fuel dilution.


That and change the oil more frequently along with testing.



Yes, I'll be on the frequent oil change routine for a while. At 3,000 miles the oil is still in-grade (barely) and wear metals look OK. But if I went with Honda's IOLM which typically points to a 10,000 mile OCI...

 

[bigt61]

The dilution will improve with age as the rings break in. Run an OCI of 5W-20 dino or semi syn to help speed the process. 5% wont kill anything IMO, back in the carburetor days, that was nothing.

 

[Eddie]

The important thing is what was the wear values? If the ware values are reasonable then fuel dilution number is of little concern. Ed

 

[Danh]

Originally Posted By: Eddie
The important thing is what was the wear values? If the ware values are reasonable then fuel dilution number is of little concern. Ed


Iron 5
Al 2
Cu 1

No chromium, nickel, lead or tin.

Only 3,000 miles on the sample but especially given the relative youth of the engine these results seem fine. Of course this doesn't mean I can't worry about it...

 

[KrisZ]

Run the heck out of it every once in a while, DI especially is bad at low RPM for properly atomizing the fuel. That's why some automakers have port injection as well, but most of the internet thinks it's for intake valve deposits. It is not.

 

[badtlc]

Try premium unleaded if you are interested in experimenting.