E85 Occasional use in FlexFuel Vehicle?

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Phishin

Joined
May 1, 2012
Messages
2,925
Location
Indiana
My 2018 Silverado 3500 with 6.0L gas engine is the FlexFuel variant. Every 30k miles or so, I run a few tanks of E85 through it. My thoughts are that the solvency of the ethanol might help clean varnish/deposits in the fuel tank, fuel lines, injectors, and maybe even the combustion chambers.

Is there any proof that this happens? I've came up with various "guesses" found on the 'net. I was curious if I was wasting my time or even possibly causing harm by even putting E85 in my truck for a few days.....
 
Phishin said:
My 2018 Silverado 3500 with 6.0L gas engine is the FlexFuel variant. Every 30k miles or so, I run a few tanks of E85 through it. My thoughts are that the solvency of the ethanol might help clean varnish/deposits in the fuel tank, fuel lines, injectors, and maybe even the combustion chambers.

Is there any proof that this happens? I've came up with various "guesses" found on the 'net. I was curious if I was wasting my time or even possibly causing harm by even putting E85 in my truck for a few days.....
Click to expand...
Yes E85 does in fact clean the injectors and intake valves.....at least that is what I found with the car in my signature. I recently pulled the head to replace the headgasket and the injectors and intake, and exhaust valves were super clean. There was some carbon on the piston tops, but it was easily cleaned with some Brake Clean and an old tooth brush. My vote would be to keep doing what you are doing.
 
Just make sure that when you switch to E85, either run several tanks or manually reset the learned ethanol content data within the PCM. It takes quite a while for the ethanol sensor to recognize and update the information in the PCM, very important for fueling.
 
14Accent said:
Just make sure that when you switch to E85, either run several tanks or manually reset the learned ethanol content data within the PCM. It takes quite a while for the ethanol sensor to recognize and update the information in the PCM, very important for fueling.
Click to expand...

Yeah, a few interesting videos/case studies about vehicles with check engine light codes or major driveability problems due to incorrect ethanol percentage. Fascinating how bad the programming of the cars really is lol. Oh well, I've never had anything FlexFuel but all gas around here is E15 so I guess the engine should be plenty clean?
 
I’m not sure if it helps but I use it every once in a while too as long as it makes sense per gallon. Right now it’s 25% cheaper here and I get about 25% less mpg so it works. Have a tank of it right now in the Grand Cherokee.

Have been hoping it cleans though.
 
I'll run a tank through my flex fuel Ranger if it is cheap enough.
It runs like a different vehicle with the E85 in it.
I haven't put any in it for several years, so I can't remember the mileage difference.
I do remember that I calculated that there had to be a 70 cent/gal spread in price to break even on it from a cost perspective.
 
14Accent said:
Just make sure that when you switch to E85, either run several tanks or manually reset the learned ethanol content data within the PCM. It takes quite a while for the ethanol sensor to recognize and update the information in the PCM, very important for fueling.
Click to expand...
I always run two full tanks of E85 before I go back to gas. How long does it take for the PCM to adjust? Do you know how the truck knows I just filled up with Ethanol?
 
Phishin said:
I agree. It's the Dodge and Ford's that take forever to "learn". GM's know immediately because of the ethanol sensor.
Click to expand...

I know the '14 & up 1500's have Alcohol Content Sensors....But what I've seen on '14 & up 2500/3500 is they calculate Alcohol Content Virtually. Not that I'm 100% on a '18 model.

ALL Flex Fuel '07-'13 GMT900's used a Virtual Flex Fuel Algorithm, As did the late GMT800's, Early GMT800's used a Alcohol Content Sensor.
 
Phishin said:
I was curious if I was wasting my time or even possibly causing harm by even putting E85 in my truck for a few days.....
Click to expand...
If it was at least 20% cheaper than regular I'd run it all the time. Higher octane than premium so engine makes more power, burns cleaner so engine and oil stays cleaner.
 
Well, I've decided to make a 500-700 gallon run of E85 through it this time. With HPL 5w40 SuperCar in the oil pan, I'll keep the 5k mile OCI's. Truck seems to run great.
 
The Critic said:
False. Ethanol is extremely corrosive to crankcase complements. When running E85, Toyota requires cutting the OCI in half.
Click to expand...

Is that because ethanol is actually corrosive OR because more of it is needed to go the same distance OR a little of both?

Based on the theory that engine oil life is dependent more upon gallons of fuel used than it is distance driven, use of E85 would require more frequent oil changes when changing oil based on distance driven, simply because a gallon of E85 doesn't go as far.
 
brianl703 said:
Is that because ethanol is actually corrosive OR because more of it is needed to go the same distance OR a little of both?

Based on the theory that engine oil life is dependent more upon gallons of fuel used than it is distance driven, use of E85 would require more frequent oil changes when changing oil based on distance driven, simply because a gallon of E85 doesn't go as far.
Click to expand...
My understanding of E85 matches his:

626,000 mile Pentastar teardown

Originally Posted by OIL_UDDERNice! As an former Pentastar design engineer I am slightly bias but the engine is really high quality. Few points from the development using tens of millions of dollars in analysis and testing regarding the oil and durability..... The lighter oil was chosen mostly...
bobistheoilguy.com

E85 can negatively impact engine wear for a multitude of reasons, some of which he highlights in his post.
 
Phishin said:
I agree. It's the Dodge and Ford's that take forever to "learn". GM's know immediately because of the ethanol sensor.
Click to expand...
Our 2018 Grand Caravan can jump between the 2 with no issues. I’ve done almost entire tanks (~18 gallons of E85+2’ish gallons of 87 E10) then immediately switched back to 87. Only difference was fuel economy dropped to about 15’ish on E85 and immediately jumped back up to 18’ish on 87, but it felt peppier running E85.
 
brianl703 said:
Is that because ethanol is actually corrosive OR because more of it is needed to go the same distance OR a little of both?

Based on the theory that engine oil life is dependent more upon gallons of fuel used than it is distance driven, use of E85 would require more frequent oil changes when changing oil based on distance driven, simply because a gallon of E85 doesn't go as far.
Click to expand...
It is corrosive to aluminum and rubber but most of its damage is due to the hygroscopic properties.
 
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