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

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OP qualifies as Severe Service. Toyota says change the oil at 5k mile intervals. I would use a MityVac and do a partial change at 2.5k mile intervals. That will replenish the add pack plus keep the fuel dilution near 4%. Use TGMO, M1 AFE, or PP 0W16.

180k miles of experience with the 2.0L version of OPs engine here.

The cause for concern is OPs driving conditions, featuring frequent short term trips, and non highway driving. Fuel dilution problems can thus be dissipated with confidence.

Otherwise, OPs comfort zone leads to the conclusion that this buyer-craved RAV4 Prime should be traded in on a non Hybrid RAV4.

$0.02 worth.
 
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Don't have a rav 4 prime. But I do have a Prius prime. And I can tell you that I don’t run the motor enough to burn off the fuel that seeps passed the rings at cool temperatures.

If you want to try and control your oil dilution. Use your engine more. Very little short tripping.

I understand saving money and using the electricity around town. But you need to get out to highway speeds for at least 8-12 miles every few days if you want a handle on it. Or just learn to live with it.

I just decided I’d start changing my oil every 6 months to combat it.
 

Shel_B

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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.
Thanks for your prompt and thorough response.

So, a more thorough way to address the issue, apart from thicker oil, is to find an oil with an additive pkg better able to combat, or mitigate, the effects of gas in the oil. To be clear, I'm not suggesting that an oil can cure, or fix, the problem (although that would be nice), just to stand up better to the fuel diluting the oil.

Is there such an oil that you're aware of?

From what I picked up at the HPL meeting, a standard API-rated oil may not have what it takes to go 5,000 or more miles ... at least in certain instances.
 

Shel_B

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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.
Wear metals may be good, but do they tell the whole story? As @OVERKILL noted, the additive package may suffer as well, and I, for one, don't yet understand how that may affect engine health over the long term. Do you have any thoughts on that?
 
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Wear metals may be good, but do they tell the whole story? As @OVERKILL noted, the additive package may suffer as well, and I, for one, don't yet understand how that may affect engine health over the long term. Do you have any thoughts on that?


Nope.
 

OVERKILL

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OVERKILL

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Thanks for your prompt and thorough response.

So, a more thorough way to address the issue, apart from thicker oil, is to find an oil with an additive pkg better able to combat, or mitigate, the effects of gas in the oil. To be clear, I'm not suggesting that an oil can cure, or fix, the problem (although that would be nice), just to stand up better to the fuel diluting the oil.

Is there such an oil that you're aware of?

From what I picked up at the HPL meeting, a standard API-rated oil may not have what it takes to go 5,000 or more miles ... at least in certain instances.
Problem is that more robust additive chemistry; higher levels of AW additives are not permitted for most grades under API rules. The Euro approvals are more generous in that department.
 

Shel_B

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Problem is that more robust additive chemistry; higher levels of AW additives are not permitted for most grades under API rules. The Euro approvals are more generous in that department.
That's kind of in the direction I was going with the question. Discussions at HPL shed some light on the quality of many oils that carry the Starburst label.
 

cdherman

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It is only in todays strange market where I could theoretically sell the vehicle for more than I paid and then get in line for a Hybrid which does not have the same potential for fuel buildup in the oil.

I think the mention by many that my driving qualifies as "severe duty" is quite the hoot! Toyota thinks the Prime can go 10k miles between oil change, and there are many users over at RAV4WORLD that talk about going longer, since their actual miles on the gas engine are much less. Most of the time, for short trips, the gas engine never is used. It remains entirely cold. The vehicle is sound proofed well enough that sometimes the ICE comes on without being heard as road noise exceeds engine noise. But the driver is alerted to the event either by the computer screen if you have it set to that view, or the "remaining miles" gas gauge will tick down a mile or two, cluing you in that the gas engine ran.

But as I said in original post, mostly I have driven long stretches in HV mode, and short trips in pure EV.

The oil dilution issue is what has me really troubled.

Current plan as of today is change the oil that is in there, Mobil 0w16 is the plan. New filter too. I will try my hardest to avoid any gas engine use unless the vehicle is going to be driven for at least 30 minutes at highway speed. And after a 3-4 k more miles, I'm going to resample. If there is fuel in the oil again, I'm selling it.

Not interested in being part of a debacle 11 years from now. Toyota makes mistakes once in a while too.
 
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Toyota tends to use very thin base oils with a lot of VII. That doesn't scream "quality" to me, FWIW.
That's not what he asked, he was asking for an oil with a stronger additive package which might help mitigate the issue.
"So, a more thorough way to address the issue, apart from thicker oil, is to find an oil with an additive pkg better able to combat, or mitigate, the effects of gas in the oil."

I responded with an oil which seems to have a robust additive package. If you feel that an oil with better base oils and less vii is the answer, then by all means, suggest a different oil to him.

Edit: I'm also out of the loop a bit here, I don't come here much these days. I've searched through your posts to try and find more info about your claims that TGMO is light group III with a lot of vii, and mobil 1 is largely pao with very little vii. How did you determine this? I see the noack differences between M1 and TGMO 0w-20, but I haven't seen anything for 0w-16.
 
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1. OP is "Severe Service" as a frequent short tripper.
2. Fuel dilution concerns here are exaggerated and are mitigated by changing the oil more often.
3. Viscosity is not king in combating fuel dilution per HPL Open House panel discussion.
 
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Shel_B

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That's not what he asked, he was asking for an oil with a stronger additive package which might help mitigate the issue.
"So, a more thorough way to address the issue, apart from thicker oil, is to find an oil with an additive pkg better able to combat, or mitigate, the effects of gas in the oil."

I responded with an oil which seems to have a robust additive package. If you feel that an oil with better base oils and less vii is the answer, then by all means, suggest a different oil to him.

Edit: I'm also out of the loop a bit here, I don't come here much these days. I've searched through your posts to try and find more info about your claims that TGMO is light group III with a lot of vii, and mobil 1 is largely pao with very little vii. How did you determine this? I see the noack differences between M1 and TGMO 0w-20, but I haven't seen anything for 0w-16.
Who is "he?" There are a lot of people in this thread asking similar questions.
 
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Who is "he?" There are a lot of people in this thread asking similar questions.
You. I will often not use quotes like I did here when I'm responding to person directly above me. I thought it was clear I was referring to you since you asked about an oil with better additive package, and I responded right below with tgmo oils which appear, on paper to have good additive packages. Sorry for the confusion.
 

Shel_B

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You. I will often not use quotes like I did here when I'm responding to person directly above me. I thought it was clear I was referring to you since you asked about an oil with better additive package, and I responded right below with tgmo oils which appear, on paper to have good additive packages. Sorry for the confusion.
OK, thanks for clarifying. Actually, that snippet of conversation with @OVERKILL was taking place on two levels, and the unspoken subtext, which became evident in a subsequent message, was really the point of my comment. The question, while not appearing rhetorical, was in fact so within the context of the unspoken subtext.

I'm having a little amusement, but again, thanks for clarifying.
 

OVERKILL

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That's not what he asked, he was asking for an oil with a stronger additive package which might help mitigate the issue.
I was responding to your claim that the oil had a "stronger" additive package, just pointing out that the oils aren't formulated to be "robust" in terms of base oil selection. But, to your point, I'm not seeing it in the links you posted. What, in particular, are you using to make that determination?
I see, for the 0W-20:
- Phosphorous right in the middle of the road at 750ppm
- Calcium and magnesium at pretty typical levels

Only thing that stands out might be the higher level of moly?

The 0W-16 looks pretty much the same.
"So, a more thorough way to address the issue, apart from thicker oil, is to find an oil with an additive pkg better able to combat, or mitigate, the effects of gas in the oil."

I responded with an oil which seems to have a robust additive package.
Again, I welcome your input on what part of either of those VOA's show a more robust oil, beyond just having more moly. I'm just not seeing it.

An oil with less VII is going to be less prone to viscosity loss through shear, particularly if the VII it does have is of a higher quality, which most OTS oils don't use. If you are already experiencing viscosity loss through fuel dilution, this is helpful in minimizing overall loss.
If you feel that an oil with better base oils and less vii is the answer, then by all means, suggest a different oil to him.
I was responding to you, not the OP.
Edit: I'm also out of the loop a bit here, I don't come here much these days. I've searched through your posts to try and find more info about your claims that TGMO is light group III with a lot of vii, and mobil 1 is largely pao with very little vii. How did you determine this?
Well, let's first look at the TGMO 0W-20 VOA you linked:
- High volatility at 12.9%
- High viscosity index of 227

Both of those things point to very light base oil with very high VII content.

In comparison, the pre-revision version of M1 EP had a low VI (though how low is up to debate, there's some question as to the accuracy of the KV40 figure Mobil was claiming) which pointed to little to no VII in the product. The thread on this oil can be found here:
I see the noack differences between M1 and TGMO 0w-20, but I haven't seen anything for 0w-16.
Mobil's 0W-16 was almost entirely PAO, so would require little to no VII:
1662061846550.png

Unfortunately, they do not publish KV40, so we can't calculate the VI to confirm.

The TGMO 0W-16 details posted by SK showed Noack at 13%, so essentially the same idea as the 0W-20, which implies it's a similar style base oil blend (it looks like basically the same oil) with a bit less VII.


So, if we circle back to the OP's issue, assuming we want to stay with a 0W-16, our options are limited. AW chemistry is of course limited by the API and most oils are going to be very similar in this regard. So, the only real avenue we have to reduce viscosity loss is to do so from other sources like shear, which means AFE 0W-16 is probably a "better" choice. If we are willing to go a bit heavier, expanding our options to a 0W-20, then the scope of available offerings is expanded a bit. M1 HM/EP HM has a bit more phosphorous at 800ppm, but if we look at the Euro offerings, M1 ESP X2 0W-20 has 880ppm, the most "robust" 0W-20 they offer.

I'd expect we would see similar from other Euro 0W-20's, so, if he's interested in a more robust lubricant with no real risk, a Euro 0W-20 with Porsche C20, VW 508 00/509 00 and MB 229.71 would be a great starting point.
 
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Only thing that stands out might be the higher level of moly?
First and foremost I appreciate the detailed reply.

Yes, I didn't say that and I should have. In my mind I was wondering, will the extra moly in TGMO be beneficial in vehicles with elevated fuel dilution. I've read speculation about M1 using trinuclear moly where less is required to do the job, but I haven't seen any proof of that. But again, I don't come here much these days if proof has been posted.

I guess ultimately my feelings on the subject are that it doesn't really matter which oil you go with if you have fuel dilution issues. Personally I'd go with the cheapest synthetic I could find, and just change it more often.
 

OVERKILL

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First and foremost I appreciate the detailed reply.

Yes, I didn't say that and I should have. In my mind I was wondering, will the extra moly in TGMO be beneficial in vehicles with elevated fuel dilution. I've read speculation about M1 using trinuclear moly where less is required to do the job, but I haven't seen any proof of that. But again, I don't come here much these days if proof has been posted.

I guess ultimately my feelings on the subject are that it doesn't really matter which oil you go with if you have fuel dilution issues. Personally I'd go with the cheapest synthetic I could find, and just change it more often.
You are quite welcome!

I doubt the moly will be of any real help, while it does provide some AW protection, it's mostly for FM. There really is no replacement for ZDDP, despite it being a PITA to work with, lol

Infineum, which both Mobil and Shell use for their additive packages (and co-own) was the company that supplied/supplies trimer moly and had put out a presentation on it. There have been some of the slides from it posted. The lower levels of moly we see from both Shell and Mobil does tend to point to them using trimer, particularly when coupled with the fact that they have easy access to it, but they have not come out and said that it is what they use.

HPL, one of our board sponsors, uses dimer and trimer moly along with tungsten. The treat rate varies depending on the oil.

Ultimately, the OP's dilution doesn't bother me as much as say a Honda 1.5L would. I tend to agree with just changing it a bit more frequently if dilution is at a level that causes concern. :)
 
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You are quite welcome!

I doubt the moly will be of any real help, while it does provide some AW protection, it's mostly for FM. There really is no replacement for ZDDP, despite it being a PITA to work with, lol

Infineum, which both Mobil and Shell use for their additive packages (and co-own) was the company that supplied/supplies trimer moly and had put out a presentation on it. There have been some of the slides from it posted. The lower levels of moly we see from both Shell and Mobil does tend to point to them using trimer, particularly when coupled with the fact that they have easy access to it, but they have not come out and said that it is what they use.

HPL, one of our board sponsors, uses dimer and trimer moly along with tungsten. The treat rate varies depending on the oil.

Ultimately, the OP's dilution doesn't bother me as much as say a Honda 1.5L would. I tend to agree with just changing it a bit more frequently if dilution is at a level that causes concern. :)
I was not aware of the tungsten !

What is impossible to miss is the very beefy dosage of magnesium (especially vs M1/TGMO), and the massive TBN retention.

It is fortunate that my circumstances allow for extended OCIs. The dipstick is examined and smelled daily. Nothing to see here.
 

cdherman

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1. OP is "Severe Service" as a frequent short tripper.
2. Fuel dilution concerns here are exaggerated and are mitigated by changing the oil more often.
3. Viscosity is not king in combating fuel dilution per HPL Open House panel discussion.
No, I am not a frequent short tripper. Most of the short trips involve the ICE engine entirely off while the electric motor does the work. Sorry if my initial post might have insinuated otherwise. Initially, RAV4 Prime drivers note the ICE kicking in randomly. Then they learn what tends to cause it. I fear Prime drivers that do not learn to avoid the random ICE use, and adhere to 10k OCI are going to lose some engines.................

Yes, the RAV4 Prime has a learning curve in terms of how to keep it from kicking the ICE on randomly. But i mostly mastered that.

Frequent oil changes are NOT without impact. There is cost, hassle and environmental impact. All of which I consider.

I am following the oil discussion, but you guys seem to split hairs and bicker mostly!!!! Using a better oil in terms of avoiding damage from fuel contamination (of the oil, to make Rand happy) would be a good idea indeed. Doubt there is much objective data on that............
 
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