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Discussion Starter · #1 ·
Hi All,

Thought I would share this, as it may help people with similar issues. After 18 months of troubling ownership of our 2020 Ascent, the issue of contamination of the engine oil with gasoline (external lab test results showed more than 10% fuel contamination) and associated reduction in fuel economy has seemingly been resolved at last - the fuel pump needed to be replaced!

K
 

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2022 Ascent Onyx, Ice Silver
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Hi All,

Thought I would share this, as it may help people with similar issues. After 18 months of troubling ownership of our 2020 Ascent, the issue of contamination of the engine oil with gasoline (external lab test results showed more than 10% fuel contamination) and associated reduction in fuel economy has seemingly been resolved at last - the fuel pump needed to be replaced!

K
The transfer pump or high pressure GDI pump?
 

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21 Ascent Premium, 18 Outback Ltd 2.5
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Can you give some more background on your issue? Like what else (if anything) did the dealer try before the fuel pump? What led them to replace the pump? Were you part of the recent fuel pump recall?

Sorry for all of the questions, but this is my biggest worry for my Ascent (though I have only 700 miles on it so far). So I'd like to learn as much as I can before I need to know.
 

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Discussion Starter · #5 ·
Hi,

Background:
Day 2 of ownership I checked the oil dipstick level on the Ascent - it was about 1/2 an inch above the ‘max’ mark and I also could smell gasoline on the dipstick (which raised a red flagand so the investigation started….
Apart from numerous oil and oil filter changes when the vehicle was brought back to the dealership, the following fixes were attempted before the fuel pump was finally replaced:
4 injectors replaced
ECM (engine control module) replaced

Hope this helps,
K
 

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Discussion Starter · #6 ·
Hi,

Background:
Day 2 of ownership I checked the oil dipstick level on the Ascent - it was about 1/2 an inch above the ‘max’ mark and I also could smell gasoline on the dipstick (which raised a red flagand so the investigation started….
Apart from numerous oil and oil filter changes when the vehicle was brought back to the dealership, the following fixes were attempted before the fuel pump was finally replaced:
4 injectors replaced
ECM (engine control module) replaced

Hope this helps,
K
By the way, this was not part of a recall (the dealership gave the typical comment of ‘never seeing this issue before’), the vehicle had done over 26,000 miles when the fuel pump was replaced.
I hope that this oil dilution with gasoline will not affect the longevity of the engine, due to reduced oil viscosity/lubrication. My dealership did extend my warranty for free but not by much.
My humble advice to Ascent owners is to check oil dipstick levels according to Subaru instructions, especially with a new vehicle and take it back to the dealership if the oil level is above the max mark, insist that your Subaru dealership do an oil change and importantly make sure they confirm where the oil level is exactly on the dipstick, in order to give you a baseline. Then follow up with checks on the oil level on the dipstick to ensure there is hopefully no issue.

K
 

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Hi All,

Thought I would share this, as it may help people with similar issues. After 18 months of troubling ownership of our 2020 Ascent, the issue of contamination of the engine oil with gasoline (external lab test results showed more than 10% fuel contamination) and associated reduction in fuel economy has seemingly been resolved at last - the fuel pump needed to be replaced!

K
What was your car doing to you to make you look into this?
 

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Discussion Starter · #10 ·
Thanks for the info @Blue Do you have any idea what led the dealer to determine it was the fuel pump?
The dealer told me they can only do what Subaru tell them to, so after they did an oil change and verified the level, then rechecked it several 100Km later and found the oil was high, the process began - injectors all replaced, Engine Control Module replaced and the the fuel pump replacement. Not sure why this sequence of attempted fixes was chosen.
 

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2022 Ascent Onyx, Ice Silver
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The dealer told me they can only do what Subaru tell them to, so after they did an oil change and verified the level, then rechecked it several 100Km later and found the oil was high, the process began - injectors all replaced, Engine Control Module replaced and the the fuel pump replacement. Not sure why this sequence of attempted fixes was chosen.
Many GDI engines "make oil". Hyundai has had problems with this. I think it could be the calibration of the injectors and too high pressure in the HP fuel pump. Hyundai/Kia has now gone to dual MPI/GDI injection to address issues with intake valve fouling. I'd like to see Subaru follow suit.
 

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If your engine is diluting the oil, then you have improper engine lubrication and your engine will suffer from it. I think this will be an issue which will cause premature engine failure and I hope Subaru considers a solution. I change my own oil and am going to start to monitor it for the limited time we have left with the car. It’s a matter of figuring out the amount the oil didn’t decrease over its change interval for people like us with no apparent gas odor or very increased oil level, but any dilution of oil will destroy the engine by causing excessive metal to metal wear.

I wonder if anyone - and some people are full of conjecture- has notified Subaru of this glaring problem.
 

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I wonder if anyone - and some people are full of conjecture- has notified Subaru of this glaring problem.
FYI it is not just a Subaru problem it is an automotive industry wide problem. Direct fuel injection in cold climates and driving short low rpm trips leading to excessive fuel dilution seems to be common on many brands and models of cars
 

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Fuel is getting into the crankcase via the piston rings not due to direct injection. Hundreds of car models have DI engines and no fuel dilution problems. Also a faulty pvc system will not add fuel in massive quantities to a crankcase like that. If the rings are faulty or not seated they will leak and the oil level will rise. As the fuel dilution worsens it breaks down the viscosity of the oil making it thinner as well as breaking down its ability to lubricate chemically. With a 0w-20 you are already on the verge of protection which is only used so manufacturers can satisfy the CAFE economy requirements. No 0w-20 is not the best oil for the engine it is only used for CAFE! Easy way to see what you should use is look up what your car model in overseas markets use. I guarantee the oil weight is spec’d differently. From revealed information Subaru lost the class action lawsuit and is now acknowledging that the piston rings are faulty. My advice is run a 5w-30 and monitor your fuel dilution via an analysis service like Blackstone until the engines are fixed. Change your oil often to keep the dilution low. If it gets as high as some have said like an increase of half inch of oil level I would have to say engine damage has been done already. That is a lot. Blackstone flags any report over .5% fuel dilution which would be undetectable in the visual oil level. Good luck and sorry modern Subaru’s are having such problems. I’m actually not surprised as 85% of all the 2.5L engines produced from 1998-2006 suffered from faulty engine design resulting in blown head gaskets. The bulletproof 2.2L engines piston diameter was enlarged which resulted in a reduced sealing surface between the head and block. Instead of redesigning the engine like they should have done they modified the 2.2L as a cost cutting measure. Millions of customers got stuck holding the bag as Subaru denied all accountability even though the engines were proven defective. That is shady business period.
 

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2022 Ascent Onyx, Ice Silver
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FYI it is not just a Subaru problem it is an automotive industry wide problem. Direct fuel injection in cold climates and driving short low rpm trips leading to excessive fuel dilution seems to be common on many brands and models of cars
Many mfg's have gone to dual injection systems, like multiport plus direct to address the problems with DI only. The intake valves will be kept cleaner by having fuel passing over them. I'm not sure how this will affect the issue of fuel dilution of the engine oil, perhaps with multiport injection, there won't be the need for an overly rich DI mixture on cold starts.
 

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Discussion Starter · #18 ·
Fuel is getting into the crankcase via the piston rings not due to direct injection. Hundreds of car models have DI engines and no fuel dilution problems. Also a faulty pvc system will not add fuel in massive quantities to a crankcase like that. If the rings are faulty or not seated they will leak and the oil level will rise. As the fuel dilution worsens it breaks down the viscosity of the oil making it thinner as well as breaking down its ability to lubricate chemically. With a 0w-20 you are already on the verge of protection which is only used so manufacturers can satisfy the CAFE economy requirements. No 0w-20 is not the best oil for the engine it is only used for CAFE! Easy way to see what you should use is look up what your car model in overseas markets use. I guarantee the oil weight is spec’d differently. From revealed information Subaru lost the class action lawsuit and is now acknowledging that the piston rings are faulty. My advice is run a 5w-30 and monitor your fuel dilution via an analysis service like Blackstone until the engines are fixed. Change your oil often to keep the dilution low. If it gets as high as some have said like an increase of half inch of oil level I would have to say engine damage has been done already. That is a lot. Blackstone flags any report over .5% fuel dilution which would be undetectable in the visual oil level. Good luck and sorry modern Subaru’s are having such problems. I’m actually not surprised as 85% of all the 2.5L engines produced from 1998-2006 suffered from faulty engine design resulting in blown head gaskets. The bulletproof 2.2L engines piston diameter was enlarged which resulted in a reduced sealing surface between the head and block. Instead of redesigning the engine like they should have done they modified the 2.2L as a cost cutting measure. Millions of customers got stuck holding the bag as Subaru denied all accountability even though the engines were proven defective. That is shady business period.
Hi All,
Curious to know how many people have found an increased oil level (above the max. mark) on the dipstick (caused by gasoline contamination) and what was the repair e.g piston rings replaced? My oil level is high again so uncertain the fuel pump replacement I had was the cause of this issue and no other fixes have been tried by Subaru. Have not seen any recall notices about this problem either?
Cheers
 

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2022 Ascent Onyx, Ice Silver
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Hi All,
Curious to know how many people have found an increased oil level (above the max. mark) on the dipstick (caused by gasoline contamination) and what was the repair e.g piston rings replaced? My oil level is high again so uncertain the fuel pump replacement I had was the cause of this issue and no other fixes have been tried by Subaru. Have not seen any recall notices about this problem either?
Cheers
No signs of dilution with my 2022 Onyx @ 11K+ miles. I've been doing 3K mile OCIs. I have the 24 month "free maintenance", so I'm letting the dealer do it at 6K intervals, with a DIY in between (only costs ~$26). So far no rise on the dipstick and no fuel smell in the oil. I should probably do a Blackstone to be sure.
 

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Discussion Starter · #20 ·
No signs of dilution with my 2022 Onyx @ 11K+ miles. I've been doing 3K mile OCIs. I have the 24 month "free maintenance", so I'm letting the dealer do it at 6K intervals, with a DIY in between (only costs ~$26). So far no rise on the dipstick and no fuel smell in the oil. I should probably do a Blackstone to be sure.
Glad your news is good! I’m thinking this may be more of an issue with the early Ascent models - 2019, 2020 manufacturing years and as such would hopefully have been resolved by Subaru (albeit covertly) for subsequent model years. Mine is a 2020.
 
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