What Makes Fuel Dilution So Harmful?

[Hyperscn64]

Since I am a 90% big city, stop and go driver who puts 8,000 miles or so per year, I know I am "severe service". I know that this can lead to fuel dilution. But what, exactly, does that do to the engine? Is synthetic oil better at preventing this? I posted here before and managed to have my neighbor change my oil with Valvoline 5 30 Max life Semi-Synthetic.


"2006 Toyota Corolla, 76,000 miles.."

 

[CT8]

The oil becomes diluted.

 

[HangFire]

Gasoline is a poor lubricant.

 

[Lolvoguy]

Originally Posted by CT8
The oil becomes diluted.

AND this prevents the oil from doing it's job of lubricating leading to accelerated engine wear.

Happened on my dad's old Volvo 245 withe the factory SU carb.
Nobody in town could tune it properly, so it needed an engine rebuilt far sooner than the previous Volvo's with FI

 

[OilUzer]

in general, any kind of dilution is bad.
dilution definition:
"the action of making something weaker in force, content, or value."

good question. iirc syn can handle dilution better.

assuming that syn is stronger than dino ... some members may disagree

therefore, based on the above definition, it will be harder to make a stronger oil weaker.

 

[CarbonSteel]

I would also assume that fuel dilution (gasoline) reduces TBN because it accelerates acid production in the oil. The combination of reduced viscosity and potential reduced TBN lowers overall life of the oil.

 

[double vanos]

Despite fuel dilution being bad, how many UOAs do we have here with it yet the numbers are good? Quite a few actually.

 

[SZR48207]

OP if you want to keep the same driving habits but reduce dilution, drive in sport mode or whatever is the opposite of economy mode. Higher revs will warm up the engine quicker which helps dilution.

 

[Hyperscn64]

I am a novice here. Thank you for that answers.

 

[Hyperscn64]

Originally Posted by Reddy45
OP if you want to keep the same driving habits but reduce dilution, drive in sport mode or whatever is the opposite of economy mode. Higher revs will warm up the engine quicker which helps dilution.


Thank you. I will try.

 

[dave1251]

Originally Posted by double vanos
Despite fuel dilution being bad, how many UOAs do we have here with it yet the numbers are good? Quite a few actually.

Likely because the amount of dilution seen in modern DI vehicles isn't enough to cause any issues.

 

[Eddie]

+1 as dave1251 alluded to. Only when dilution get to ~> 3-4% do we see any meaningful wear increase. Ed

 

[Danno]

If it was my car, I would change the oil more frequently with a less expensive Dino oil vs using a more expensive synthetic and longer oil change interval.
More frequent oci is a defense to fuel dilution.

 

[4WD]

In my Baldwin filter thread you will see I only changed the filter but not the oil … and elected to top up with a quart of HD30 to offset potential dilution. So with 7/8 of the M1 0w20 having 5k … you could see dipstick hash marks through the oil.
(have an excess of 5 year old filters from 3 vehicles on same filter).

 

[BMWTurboDzl]

"Some" fuel isn't anything to worry about especially if it occurs in a vehicle which has been short tripped in the winter and/or has a lot of miles on it. In fact it is expected based upon the operating conditions. Engine design and wear rates have a large impact on fuel dilution. Leaking injectors are another.

Oil itself won't stop fuel dilution.

I don't think your 2006 Corolla is a known diluter.

 

[Donald]

Gas is a solvent and not a lubricant.

 

[4WD]

Originally Posted by 2015_PSD
I would also assume that fuel dilution (gasoline) reduces TBN because it accelerates acid production in the oil. The combination of reduced viscosity and potential reduced TBN lowers overall life of the oil.


Yeah … I think GM knows this and puts the 7500 mile limit in play. They know good and well the lubes are better … but so much has gone the way of DI and thin oil combinations …

 

[kschachn]

Originally Posted by 2015_PSD
I would also assume that fuel dilution (gasoline) reduces TBN because it accelerates acid production in the oil. The combination of reduced viscosity and potential reduced TBN lowers overall life of the oil.

Can you explain how you think that would happen?

 

[bbhero]

Ahh this is just a hypothesis... But hydrogen atoms being separated in the combustion process especially in diluted fuel circumstances create more free separated hydrogen atoms which would cause increase in the acidity in the motor oil over time.... Which in turn would lower tbn over time in that situation... Using up more of the oils alkalinity to buffer those extra added free hydrogen atoms being added to the oil. Again just thinking off the top of my head.

 

[Mainia]

I knew when I bought my car, a 2018 Hyundai Kona AWD 1.6T that I was going to have major fuel dilution problem since I live in Minnesota, I drive 10 miles to work, and I remote start the car for 4 minutes. I also have a heavy foot and am on boost more then most. Before I bought the car I had a 10 pack of Polaris oil test kits to watch the fuel dilution problem. I am above 5% fuel dilution as per Polaris Labs secondary advanced test they don't do for you unless you force then to rerun it on a verbal oil interpretation call. There is also a guy on this site with a 1.5T Honda that had high levels too.

I run 5w-30 Mobil 1 ESP and during the winter I dump at 3,000 miles and summer 3,500 to 3,750. I don't have any wear issues and the Honda guy doesn't either, We learn to live with it and move on. It really is a non issue. I check every third oil change for wear and nothing abnormal. Some people just freak on oil dilution over on the Hyundai forms and I always say to test for wear and if you don't have any, move on. Worry more about why the sun reflex light off your metallic paint job. Yawn.