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Discussion Starter · #1 ·
Gas dilution of engine oil- I am curious how many others are out there. Do you have a gas smell coming out of the passenger-side engine compartment? Does your garage smell like gas when you pull your vehicle in? Do you smell gas on occasion on the inside of the car when a front passenger?

Any info/experiences from members of this forum is appreciated.

Below is a message I sent to my dealer in December. After additional contacts over the past few months, I am finally meeting with a field engineer late next week. I'll let you know how it goes.

Good morning-

Hope this email finds you all well! Also hoping we can get some help with the following.

I changed the oil in the Ascent yesterday (12.134 miles). The first thing I noticed was the low viscosity of the oil- I have never seen oil pour out of a drain plug that fast. It nearly overwhelmed my drain pan and splattered as it hit it spilling on to the floor of our garage. The second thing I noticed was a strong smell of gas.

Out of curiosity, I measured how much oil/gas came from the pan. It is safely over 6 quarts- the recommended amount is 4.8 quarts on the oil change. I have a gallon milk jug full, and two 1-quart oil bottles full. There is still some oil in my drain pan, plus oil that spilled out on to our garage floor- hard to estimate what spilled onto the floor- safely 4 additional oz..

We had the oil changed at Schlossman in Sept at 6,300 miles-Melissa used the shuttle service for a flight- which worked out awesome! I doubt your service techs put over 6 quarts of oil in the vehicle.

I also notice a fuel/metallic smell on occasion in the cabin, I had not thought much about it until yesterday. I had attributed it to another car or location we were at.

Reading on the forum, I see other Ascent owners have experienced what we are experiencing. My parents have a small turbocharged motor in their 2018 CRV- they are experiencing the same issue. I wonder if the equipment is being produced by the same manufacturer....

I will start monitoring the oil level future-forward. How should I document this?

We love this vehicle! The fuel economy is lower than expected, but this may be a result of diluted oil with gas. We are obviously concerned about internal damage to the motor because it is being 'lubricated' with an oil/gas solution.....and the odor inside the vehicle is concerning as well.

Please let me know how we should proceed.

Much thanks!
 

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Gas dilution of engine oil- I am curious how many others are out there. Do you have a gas smell coming out of the passenger-side engine compartment? Does your garage smell like gas when you pull your vehicle in? Do you smell gas on occasion on the inside of the car when a front passenger?

Any info/experiences from members of this forum is appreciated.

Below is a message I sent to my dealer in December. After additional contacts over the past few months, I am finally meeting with a field engineer late next week. I'll let you know how it goes.

Good morning-

Hope this email finds you all well! Also hoping we can get some help with the following.

I changed the oil in the Ascent yesterday (12.134 miles). The first thing I noticed was the low viscosity of the oil- I have never seen oil pour out of a drain plug that fast. It nearly overwhelmed my drain pan and splattered as it hit it spilling on to the floor of our garage. The second thing I noticed was a strong smell of gas.

Out of curiosity, I measured how much oil/gas came from the pan. It is safely over 6 quarts- the recommended amount is 4.8 quarts on the oil change. I have a gallon milk jug full, and two 1-quart oil bottles full. There is still some oil in my drain pan, plus oil that spilled out on to our garage floor- hard to estimate what spilled onto the floor- safely 4 additional oz..

We had the oil changed at Schlossman in Sept at 6,300 miles-Melissa used the shuttle service for a flight- which worked out awesome! I doubt your service techs put over 6 quarts of oil in the vehicle.

I also notice a fuel/metallic smell on occasion in the cabin, I had not thought much about it until yesterday. I had attributed it to another car or location we were at.

Reading on the forum, I see other Ascent owners have experienced what we are experiencing. My parents have a small turbocharged motor in their 2018 CRV- they are experiencing the same issue. I wonder if the equipment is being produced by the same manufacturer....

I will start monitoring the oil level future-forward. How should I document this?

We love this vehicle! The fuel economy is lower than expected, but this may be a result of diluted oil with gas. We are obviously concerned about internal damage to the motor because it is being 'lubricated' with an oil/gas solution.....and the odor inside the vehicle is concerning as well.

Please let me know how we should proceed.

Much thanks!
please keep us posted
 

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Discussion Starter · #3 ·
Sorry for the duplicate thread. I see this has been posted before.
 

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I will respond to your thread since it has the latest activity.

I have a 2020 Ascent with approximately 6000 miles. I too have experienced fuel dilution of the oil from basically day one. I even changed my oil early thinking that it may have been overfilled at the factory and to be able to monitor the oil level with a known baseline. Within a 100 miles or so, the oil level was back above the full mark. After I took the vehicle in for service which included an oil change by the dealer, the oil level was again back above the full mark in a couple of days.

Now I have not really noticed any fuel smell inside the cabin at any time, so I don’t believe that the fuel dilution “problem” is directly related to what others have experienced.

Here are my thoughts about fuel dilution in these vehicles based on the research I have conducted so far.
1. Direct Injection engines tend to have a higher occurrence of fuel dilution but certainly not in every case. My 2018 VW GTI does not exhibit this condition.
2. Quality synthetic motor oils are formulated to resist this condition but should be changed every 5000 miles or so. I would not go for a long drain interval on our vehicles or any experiencing fuel dilution.
3. The only way to know how bad the fuel dilution is to get an oil analysis, which i plan to do before my next oil change.
4. When I had my Ascent in for service they gave me a brand new Forester to drive. While I had it I checked the oil and it too had an oil level over the full mark.
5. This was my first experience with 0-20 motor oil. That stuff sure is like water when it comes out of the bottle and especially as it shoots out of the oil pan and splatters everywhere. After my oil analysis, i may consider a thicker oil.
 

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5. This was my first experience with 0-20 motor oil. That stuff sure is like water when it comes out of the bottle and especially as it shoots out of the oil pan and splatters everywhere. After my oil analysis, i may consider a thicker oil.
I highly recommend using the factory recommended oil. It is practically like water when it’s new especially, but they recommend it for a reason.
 

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Yes. The reason is fuel economy.
That's the most prominent claim I've seen, though, I have also heard that it helps lubricate the turbo quicker and easier, including in colder temps - thus prolonging the life of the turbo.
 

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That's the most prominent claim I've seen, though, I have also heard that it helps lubricate the turbo quicker and easier, including in colder temps - thus prolonging the life of the turbo.
The 0 part of 0-20 would help with startup and cold temps but not the 20. Same as 0-30.
The STI still calls for 5-30.
Subaru synthetic oils are suppose to be very good. It just concerns me a bit running a 0-20 weight oil in a turbo. The used oil analysis should tell me how it is holding up.

I have also read that Mobil 1 EP 0-20 holds up well to fuel dilution given that you stick to the 5000 mile change interval.
 

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I've heard horror stories about Mobil 1 oil in Subies. I'm sticking with Idemitsu for Subaru.

0w-20 stays thinner in colder temps (or any temps) when it warms up. That's simply the nature of having a smaller viscosity range.
 

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Yea sure. There were stories about guys with WRX’s and STi’s having problems with Mobil 1 5w-30 shearing badly due to turbo heat about 8-10 years ago. That oil was too thin for their application and they should not have used it anyway. Manufacturers change oil formulations all the time and that particular grade of Mobil one is different now and not the one I mentioned. Mobil 1 EP 0w-20 is a good oil for fuel dilution (as are other oils) and should not be discounted based on “I heard horror stories”.

Spend some time on oil forums if you want to really learn about motor oil. But be careful. It is easy to get lost in there.
 

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Yea sure. There were stories about guys with WRX’s and STi’s having problems with Mobil 1 5w-30 shearing badly due to turbo heat about 8-10 years ago. That oil was too thin for their application and they should not have used it anyway. Manufacturers change oil formulations all the time and that particular grade of Mobil one is different now and not the one I mentioned. Mobil 1 EP 0w-20 is a good oil for fuel dilution (as are other oils) and should not be discounted based on “I heard horror stories”.
I had a 2010 Outback, 2.5NA. Same oil, horrible results. And it requires 5w-30. So did other NA Outback and Forester owners. It was the oil. Their 5w-30 was rated poorly compared to the competition. It was barely 5w-30, which is the reason why I won't use them again.

Perhaps they've started making great oil now, but, again, I have no intentions of taking the chance. I crossed 200,000 miles without oil consumption problems using Subaru branded Idemitsu.

Maybe their new stuff is great oil, but Idemitsu and others consistently get top marks.
 

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Spend some time on oil forums if you want to really learn about motor oil. But be careful. It is easy to get lost in there.
Been following him or in Bob's forums for many years.
 

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Yes. The oil companies all have both good formulations and not so good. Also, just because an oil works good in one engine doesn’t automatically mean it is good for all engines. Yes, I did say that the Subaru (Idemitsu) oil was good as well but you can’t just run to Walmart and pick some up either.
 

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0W20 seemed weird at first after 40+ years of 10W30/40/50 in cars and motos. It's only anecdotal and non-turbo, but my Lexus ran 0W20 with changes every 10k or 1 year (per the manual) for 10 years before getting hit and totaled. Seemed fine at the time, less than 1/2 quart oil consumption between changes at 10k and fuel mileage was good.

I'm thinking Costco 0W20 API SN PLUS for the Ascent.
 

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Hello Ascent Owners,

I have experience the same with my 2020-Ascent ( Limited -8Pas) - gas smell coming out of the passenger-side engine compartment and its intermittent. From the beginning i.e 18 miles Odometer ( Day 1 ) to till date, I have 8,500 miles on it. I changed the oil ( DYI ) at 4,500 just in curiosity but it never stopped. Did any body approach to Subaru of USA with a claim on this !! I dont see local dealership helpful at all on this matters..
 

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Hello Ascent Owners,

I have experience the same with my 2020-Ascent ( Limited -8Pas) - gas smell coming out of the passenger-side engine compartment and its intermittent. From the beginning i.e 18 miles Odometer ( Day 1 ) to till date, I have 8,500 miles on it. I changed the oil ( DYI ) at 4,500 just in curiosity but it never stopped. Did any body approach to Subaru of USA with a claim on this !! I dont see local dealership helpful at all on this matters..
I am one of the early complainers about this, but I wasn't quite the squeaky wheel that others were who got a buy back because of rising oil (due to fuel mixing in) and fuel smell in and around the car. Subaru used these buy backs apparently to try to figure it out and have deemed it "normal" due to the direct injection, so they didn't do anything for me and my local dealership was actually flabbergasted about it (I had a claim).
Shortly after this, the fuel pump recall came out and I thought, "hmmm, wonder if this will help." So I had that done and then my 24k oil change shortly after. I'm happy to report, my oil has stayed exactly where it was at the change a few months ago and my garage isn't fumy, for the first time ever.
 

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^^^ Interesting that fixing the low pressure fuel pump problem of the impeller cracking and stopping/slowing fuel circulation to the engine's high pressure pump would have an effect on fuel smell or fuel accumulating in the engine sump. I guess there could be something going on that's not straightforward or obvious.
 

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Thread revival... my 2020 ascent has been experiencing the same: strong fuel odor through vents if not on recirc, outside smells like fuel, engine bay smells like fuel, oil level up to the twist in the dipstick and strong oil smell From the oil. Taking in tomorrow for first oil change and to have the smell addressed. Doesn’t seem like there is any consensus what may cause the issue, curious where this will go....
 

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Brought my '20 touring in for first oil change yesterday. 7 months, 800 miles (they insisted on going by calendar not miles). I told the service writer that the oil level was high and smelled like gas. Checked the level this morning after sitting all night and the level is exactly where it was before the change. Still smells a bit like gas. Seems like they are adding a measured amount but don't wait long enough to drain before refilling.
 

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Hello Everyone- I started this thread six months ago. I have been dealing with the oil dilution and gas smell for over a year now.

Honestly, it started right away and it wasn't until I changed my own oil that I became aware of it- 2nd oil change. I initially blamed the smell on other vehicles- our car was brand new...

I have been in conversation with Keith Cooke (a field engineer in the mid-west based out of Iowa). He is claiming the fuel in the oil is not an issue and that they engineered the vehicle to handle gas diluting the oil. If this came from an independent research firm, I might buy it. Subaru has a whole lot of liability if they admit that gas should not be entering the oil pan and decreasing the lubricity of the oil.....leading to premature wear of an engine. Blackstone says any dilution of 2% or more indicates a problem, mine was a 4.5%.
6345


As for the smell, he changed a few parts- not sure what they were exactly- have service record with numbers and added some extra insulation...it worked for a while, but now the smell is back.

The car is going back in next Monday....don't know what they will try.

I am curious about the fuel pump recall- I have never received a notice- how does one find out about this?

One thing that is wearing on me is they don't follow up. Any further engagement is consistently initiated by me. It is disappointing and frustrating. There are many things we love about this car. However, I couldn't recommend the vehicle or Subaru because of these issues that continue to persist...why do they continue to produce a vehicle that they know has issues- especially an issue that results in families inhaling gas fumes in the vehicle if they don't open up the windows.
 
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