Fuel dilution - how harmful, how much wear?

[Nuclear_42]

Which is it, shear or dilution? I don't think I understand your answer either.

Fuel dilution is a multifaceted problem but the primary effect is simple viscosity reduction. No oil retains viscosity better than another when diluted by a lower-viscosity fluid.

And if you really are talking about mechanical shear resistance then that is not directly related to the base stock. Oil molecules do not shear in an engine.

I probably misspoke. I’m talking about dilution. Sure oil dilutes. However many oils with 4-5% remain within their weight spec range.

 

[SC Maintenance]

Now what's the effect of 4-5% plus on the engine seals/ gaskets overtime

Nitrile rubber and Viton I thought were gasoline resistant? Aren't those the two most common seal materials? Of course I have no idea if its all seals?

 

[DirectRejection]

"The amount of fuel that contaminates the lubricant depends on...lubricant type."

"At higher temperatures, gasoline fuel dilution levels will decrease, firstly due to evaporative losses and secondly as lubricant viscosities are lower too."

(Emphasis added.)

The phd's have postulated.

 

[DirectRejection]

From what I've seen your endeavor to be "precise and modern" hinges on $30 spectrograph analyses to show how safe fuel dilution is. That tells me everything I need to know about your ability to move anyone past "dipstick freakout".

My methodology of successive, further extended OCIs begins to provide a window.

There are no exhorbitant claims here.

Meanwhile, the miles accrue rapidly, and it is acknowledge that results do vary.

 

[DirectRejection]

Of course fuel dilution is not an issue for me.

If purchasing a new Honda, I would favor an HRV over a CRV.

HRV has a durable, 2.0L PFI engine at 30 mpg.

CRV has the 1.5T GDI engine with 40 mpg.

 

[bigjohann]

Carbon buildup and oil dilution are exactly not related. However, carbon buildup due to GDI is GENERALLY known to cause buildup in most GDI engines, broadly speaking. Oil dilution is just a boogeyman and not shown to have any adverse effects whatsoever. These people will parrot the same tired “do you think fuel is good in your oil” line, while not being able to actually show any evidence of engine damage or excess wear. UOAs won’t show that though, nor will taking apart an engine, but you should just trust these geniuses with zero proof!

I think there is a correlation between oil dilution and carbon buildup. The thinning of oil due to gasoline increases leaks and increases carbon due to EGR. But there are a lot of variables, especially in Direct Injection engines.

 

[demarpaint]

I would encourage those that think fuel dilution/fuel in oil "doesn't matter" to dump 1 cup of fresh gas into their new oil next change. There is simply no way this is not harmful at some level (that's where the dicussion starts) vs. not having that fuel in there. Most modern cars have minor fuel in the oil at the end of a change cycle. Folks are using UOAs to justify it not being an issue but UOAs aren't going to show the harmful effects of egregious fuel dilution I'm afraid...

I agree 100%.

 

[DirectRejection]

It is a problem with some engines, not only limited to extended oil change intervals, although they certainly don't help. One Honda Accord 1.5L turbo that I rented gained almost a quart of oil during my week long rental. It was warm out, I drove it on the highway quite a bit, and yet the oil level increased.

The oil is neither tolerant or intolerant of the fuel dilution. However, the oil's viscosity will be affected. Would I be concerned if the Accord was my car? Of course! I'd probably use a 5W-30 oil instead of the 0W-20, I would also change the oil frequently.

Yes the fuel evaporates, at some rate. Clearly, the Honda's rate of evaporation was insufficient for the crankcase filling "blowby". But even if it evaporates at a high rate, there are remnants of the fuel circulating in the oil. The oil change is the only way to remove those contaminates.

There is a reason certain engines are experiencing early timing/balancer chain failures. Low viscosity is chief among them.

Did you check the dipstick at the beginning of your rental ? I am honestly concerned about confirmation bias.

 

[ChrisD46]

If GDI Engine : Oil changes at 4K ~ 5K miles using a top tier brand SP , D1/Gen 3 rated synthetic 5W30 oil are best for a GDI engine along with treating intake valve deposits every other oil change .

 

[ZeeOSix]

Oil dilution is just a boogeyman and not shown to have any adverse effects whatsoever.

Do some research.

https://www.google.com/search?client=firefox-b-1-d&q=fuel+dilution+effect+on+engine+wear

 

[SavetheRimBrake]

Do some research.

https://www.google.com/search?client=firefox-b-1-d&q=fuel+dilution+effect+on+engine+wear

That doesn’t show any actual effects, but thank you for the in depth research you showed

 

[ZeeOSix]

That doesn’t show any actual effects, but thank you for the in depth research you showed

If you actually took the time to open some of those links and research it, there is some information about dilution % levels where damage occurs. Anything over about 5% dilution isn't doing any engine any good.

 

[SavetheRimBrake]

If you actually took the time to open some of those links and research it, there is some information about dillution % levels where damage occurs. Anything over about 5% dilution isn't doing any engine any good.

It may not be ideal, but it doesn’t actually make any practical difference. Also most people will never see 5% dilution anyway

 

[ZeeOSix]

It may not be ideal, but it doesn’t actually make any practical difference. Also most people will never see 5% dilution anyway

If people were seeing 5% or more fuel dilution (and some do), then it certainly can make "a practical difference" in engine wear. Especially if they are running a thin oil like xW-8 thru xW-20 and running longer OCIs. Those have been main points through this whole thread.

So you would be OK running a 0W-20 or 0W-16 oil with over 5% fuel dilution for a 10K OCI? I sure wouldn't.

 

[TiGeo]

It may not be ideal, but it doesn’t actually make any practical difference. Also most people will never see 5% dilution anyway

I finally figured it out....savetherimbrake (current name...was cleanneon98 a few days ago) is also....fuselli!

The fuel dilution rhetoric similarity is uncanny....

 

[DirectRejection]

If people were seeing 5% or more fuel dilution (and some do), then it certainly can make "a practical difference" in engine wear. Especially if they are running a thin oil like xW-8 thru xW-20 and running longer OCIs. Those have been main points through this whole thread.

If the issue is loss of viscosity from fuel dilution and only that, doesn't oxidative thickening counterbalance that ? "Masking" has been a known issue for many years.

If there is the additional issue of depletion of add pack ingredients, then my preference would be to use highest quality oil. A fluid extractor can be put to use cycling in one or two quarts of fresh oil from time to time.

The synthetic base stocks and robust, replenished premium add packs defeat the issues associated with oxidative thickening, as well as the other negatives.

This is cost effective, or at least not as expensive as it would seem.

Meanwhile the only argument I am seeing against this is "MOFT blah, blah, blah", and a snarky " 3ppm Fe don't mean squat."

There are modern solutions out there, especially for modern cars. We will be into the next categories beyond SP/GF-6 before long.

 

[ZeeOSix]

I finally figured it out....savetherimbrake (current name...was cleanneon98 a few days ago) is also....fuselli!

 

[SubieRubyRoo]

I finally figured it out....savetherimbrake (current name...was cleanneon98 a few days ago) is also....fuselli!

The fuel dilution rhetoric similarity is uncanny....

It’s a shame they quit teaching the importance of understanding the scientific method to grade schoolers. Maybe someday (likely when he loses an engine) he’ll learn that fuel dilution >5% starts risking accelerated wear that’s likely too big to be detected by a UOA.

 

[TiGeo]

View attachment 173817

Yes I know that it sounds like same person/2 accounts....seems to be popular lately.

 

[medunko]

A had a similar topic concerning supposed oil dilution with Toyota Yaris 2006 , build in France - 2sz fe, 90 % of time short tripped, oil sump - 3,2 litters. The oil is turning diesel black after few months and smelling gasoline. The head gasket sealant is for change too,
Long story short - just change the oil more often with some expensive 5w30, not boutique oil, for example Mobil, valvoline, amsoil … well known internationally brands.