Fuel contamination in a new RAV4 Prime PHEV. Thoughts? Advice?

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OK, the RAV4 Prime is Toyota's second Plug In Hybrid Vehicle (PHEV) and has about 45 miles of battery only range. Thereafter it switches to Hybrid vehicle (HV mode) since it "saves" some battery to allow continued hybrid use, in conjunction with the A25A-FXS atkinson cycle 2.5l NA 4 cylinder engine with both direct injection initially, then later port inject once warmed up.

Due to other reports of fuel dilution, I pulled a sample and after conferring with ALS Tribology, they were able to do gas chromatographic testing for fuel contamination. Unexpectedly, after less than 2000 miles of gasoline engine running (4000 total miles on vehicle) I am showing 4% contamination. Rest of UOA was fine.

The ICE kicks in "early" occasionally a variety of settings for a minute or so. Not long enough to really heat up the engine oil, but perhaps long enough to get some gasoline by the piston rings.

I have largely figured out how to avoid the brief starts, and now have pretty much mastered driving the vehicle so that the engine either stays full electric or is switched to HV mode and stays there for the remainder of the drive, thus ensuring full operating temperature.

Does anyone have any other theories what could be going on?

This is a BIG deal to me. Having read about some of the problems that Honda has had. The RAV4 Prime is expensive and hard to get. It really only pays for itself over many years of use, compared to just a hybrid. I want mine to run 200,000 miles at least and if its going to crap out at 120,000 due to a failed engine, well that would really disappoint..
 

OVERKILL

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I have never heard of a 1.5T engine failure in a CRV or civic. The actual affect of fuel dilution is largely overblown here in my opinion. Don't let it stop you from enjoying your vehicle.
The Chinese government imposed a stop sale and forced a recall on vehicles with this engine because there were so many problems related to the fuel dilution of the oil.
Chinese regulators ordered a recall to repair 350,000 1.5L-equipped vehicles, even in regions where consumers were unlikely to experience the condition, Honda says.

There's also a class-action lawsuit over the issue, citing problems such as engine failure as the result (also mentioned in the previous Ward's article):
 

cdherman

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I would just change the oil more often!
Well, that is an option. Or sell it. Sadly kind of for buyers at least, the current state of affairs says I can sell it for $10,000 over what I paid for it. That makes one consider one's options. Like, maybe a plain old hybrid instead.

I have grown to hate oil changes. Messy, bad for environment. And if there is fuel in the oil all the time, that has to mess up viscosity. Cannot figure out how to find my Oil analysis that I edited to remove personal information. Elsewise, I'd post it.

Considering running 0w20 after warranty expires. But if I decide to keep the vehicle, I'd probably opt for a 10 year extentended warranty. Which further worsens the already horrendous price I paid for it.

And if Rand with 18k plus posts is so smart about the engine, perhaps he'd like to explain instead of just posting how "wrong" I am about everything. I agree, with the oil contamination quip. OK its fuel in the oil contamination. Jeeze. But just what more do you KNOW about that engine? Pray tell.......
 
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Years ago, I spoke to an old WWII aircraft mechanic who said in Artic conditions they thined the aircraft engine oil with gasoline so they could crank them fast enough to start. Though many aircraft back then had large oil tanks to continuously add oil to the engine to make up for the loss and that would have resulted in the oil that was in the engine being what was in the makeup tank after a bit of flying. Still in all a little bit of gasoline in the oil doesn't really seem to have a major effect on the viscosity. Do I have to admit it's not my engine I'm talking about. If it were mine I would put some type of quick drain oil valve on it like a famoto or a Volvo Max and just change the oil every 4,000 or so.
 

FZ1

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Well, that is an option. Or sell it. Sadly kind of for buyers at least, the current state of affairs says I can sell it for $10,000 over what I paid for it. That makes one consider one's options. Like, maybe a plain old hybrid instead.

I have grown to hate oil changes. Messy, bad for environment. And if there is fuel in the oil all the time, that has to mess up viscosity. Cannot figure out how to find my Oil analysis that I edited to remove personal information. Elsewise, I'd post it.

Considering running 0w20 after warranty expires. But if I decide to keep the vehicle, I'd probably opt for a 10 year extentended warranty. Which further worsens the already horrendous price I paid for it.

And if Rand with 18k plus posts is so smart about the engine, perhaps he'd like to explain instead of just posting how "wrong" I am about everything. I agree, with the oil contamination quip. OK its fuel in the oil contamination. Jeeze. But just what more do you KNOW about that engine? Pray tell.......
There you go, man. Sell it and get a, brand standin' new, regular Hybrid.
 
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The Chinese government imposed a stop sale and forced a recall on vehicles with this engine because there were so many problems related to the fuel dilution of the oil.


There's also a class-action lawsuit over the issue, citing problems such as engine failure as the result (also mentioned in the previous Ward's article):
The first article says nothing about engine failures. The class action lawsuit mentions it but has no detail. If this were blowing up engines it would be written all over.

That's all besides the point that Honda actually had a problem here that needed to be corrected. So comparing to it specifically really doesn't make sense. The only reason i mentioned Honda is because the OP did.
 
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The Chinese government imposed a stop sale and forced a recall on vehicles with this engine because there were so many problems related to the fuel dilution of the oil.


There's also a class-action lawsuit over the issue, citing problems such as engine failure as the result (also mentioned in the previous Ward's article):
I think the OP's problem lies here. I would further investigate the situation.
 
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Run a thicker oil that can handle a bit of fuel and be in the actual spec of the engine. 0w16 or 0w8 for that one? My truck and mazda always run a higher hot rating than published...because of towing for the truck and single oil on hand for the mazda.
 
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Since this is a brand new vehicle I wouldn’t use that first analysis as a blueprint going forward. The engine was still breaking in. I would go a couple of oil changes before running another analysis.

It’s good that the system lets you decide how the engine and battery run.

What is your driving routine? Short trips or lots of highway?
 
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I agree let, the unit get some more miles on it. UOA are ugly during wear in. My Ford settled down after it got about 7K miles on it and don't have DI and PI. I would run a more viscous oil if you are hearing excessive engine racket - not tapping but moderate rapping. I ran 10W30 QSFS as it it low on VM and its just a good lube in service.
 
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Is this the original fill? If so. Why is it still in the engine? I would change it asap and stick to 5k OCI.

And I would do it for total 5k miles driven, not just on the engine. Because the operation you described, seems pretty severe as the engine operates in the “warm up” phase which is the hardest since a lot of the anti wear additives activate with temperature.

We can all theorize what’s going on, but at the end of the day, the safest and most cost effective way is to simply change the oil.
 

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The first article says nothing about engine failures. The class action lawsuit mentions it but has no detail. If this were blowing up engines it would be written all over.
The first article mentions the class action lawsuit claims:
wards said:
The issue already has prompted at least one class-action lawsuit alleging excessive oil dilution is causing engine damage due to high wear on inadequately lubricated components.
That's all besides the point that Honda actually had a problem here that needed to be corrected. So comparing to it specifically really doesn't make sense. The only reason i mentioned Honda is because the OP did.
I only brought it up because you mentioned this engine specifically, and this engine, specifically, has had some serious issues with fuel dilution. Apparently, the most prevalent issue reported, which caused CR to red flag the vehicle (the CR-V) was stalling from the volume of fuel in the oil:

And here's the CR article:
CR said:
John German—a veteran automotive engineer and senior fellow at the International Council on Clean Transportation, who previously worked at Honda, Chrysler, and the Environmental Protection Agency—says that the problem of fuel mixing with oil probably stems from one of two causes: improperly designed fuel injectors that spray fuel directly onto the cylinder walls or the engine not heating up enough to vaporize gasoline left over in an engine cylinder.

Either could cause fuel to mix with the oil, diluting it and making it less effective at protecting an engine’s moving parts, say CR’s car experts. And over time, that could seriously damage the engine.


Gasoline is, I think we can all agree, not a very good lubricant. It also degrades the oil by increasing the rate of oxidation, diluting the AW additive chemistry and generally just making the oil less effective at doing its jobs.

I doubt the OP is experiencing anything even remotely as bad as what the Honda 1.5L produces, in terms of dilution, in his shoes, I wouldn't be overly worried unless it started to get really bad.
 
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And if Rand with 18k plus posts is so smart about the engine, perhaps he'd like to explain instead of just posting how "wrong" I am about everything. I agree, with the oil contamination quip. OK its fuel in the oil contamination. Jeeze. But just what more do you KNOW about that engine? Pray tell.......
Its not hard to use the proper terms. 99% of people reading fuel contamination are thinking you got bad gas.
Oil dilution has been discussed widely. You are overreacting. Maybe I should put in more smilies 🥴.

A 30second google shows how the toyota dual injection works.. your version sounds like what a salesman told you.
here is a good video.

Basically port injection is good for idle and low power. Direct injection is good for mid power and high power.
They are used simultaneously in many driving conditions.


Also here is a generic pic of toyotas strategy.. but it may differ slightly for your hybrid.
image_2022-09-01_115217069.jpg
 
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Shel_B

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Gasoline is, I think we can all agree, not a very good lubricant. It also degrades the oil by increasing the rate of oxidation, diluting the AW additive chemistry and generally just making the oil less effective at doing its jobs.
So, just to be clear and so I fully understand what you're saying, even if one uses a thicker oil to counteract the diluting effects of gas in the oil, the quality of the oil is still diminished in several key areas by the deleterious effects of the gas. This, of course, can lead to other problems long term.
 

OVERKILL

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So, just to be clear and so I fully understand what you're saying, even if one uses a thicker oil to counteract the diluting effects of gas in the oil, the quality of the oil is still diminished in several key areas by the deleterious effects of the gas. This, of course, can lead to other problems long term.
Yes. Gasoline is a contaminant, and the additive package has to deal with it. It's also diluting the AW chemistry and other additives, though of course the severity of that depends on how bad the dilution is. Basically, it's not something you want in your oil in large volumes, despite that fact that some getting in there is unavoidable.

This article is about diesel fuel dilution of the engine oil, but worth reading:

From the SAE:
Test results indicated that the higher the torque at the rated-power, the greater the level of fuel dilution. In a cyclic-load engine test simulating the customer drives of a target vehicle powered by the engine, the maximum level for fuel dilution was found to be up to 9%, causing significant drop in the oil viscosity. The causes for fuel dilution and impacts of it on the oil consumption and formation of carbon deports on the piston ring area, and methods for mitigating impacts of fuel dilution are discussed in the paper.

And:
The unburned fuel entering the crankcase oil causes following impacts: (1) it dilutes concentrations of the oil additives such as wear, corrosion and oxidation inhibitors, dispersants, detergents...etc

I've also posted some other articles previously on the subject.
 
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Just to throw this in, we have had a number of oil analysis reports posted here with high fuel dilution including the Honda 1.5 Earth Dreams motor and while the oil was impacted the wear metal readings were still very good.
 
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