Fuel dilution - how harmful, how much wear?

[kschachn]

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!

Like people that parrot that there are no adverse effects based on a completely inadequate method of determination?

It's a joke to say a UOA proves anything of the sort. It's been explained to you by multiple individuals in detail why that's the case yet here we are, again.

 

[TiGeo]

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!

One just needs to look to the CA lawsuits against Honda for their 1.5 fuel issue and Honda attempting to fix the issue on these engines as it has caused damage. Obviously this is an extreme case. Also, I've mentioned many times around the forum here in these fuel dilution threads that minor/normal fuel dilution in many turbo DI engines is perfectly normal and not hurting anything with quality oil and prudent OCIs. The UOA isn't giving you what you think w/r to wear in terms of what many folks here think you will see increased iron/aluminum when you have higher fuel dilution. Spend some time in the UOA sub-forums and you'll see this. Having a solvent in your oil at higher concentrations being "not good" should be common sense. Essentially what an engine flush product is that you aren't supposed to drive with in your oil. Why do the oil analysis labs flag fuel above certain thresholds?

 

[SavetheRimBrake]

Honda attempting to fix the issue on these engines as it has caused damage.

Do you have anything that shows said damage? I’d be willing to look at some photos or physical evidence, not listen to someone regurgitate the same tired theory

 

[TiGeo]

Do you have anything that shows said damage? I’d be willing to look at some photos or physical evidence, not listen to someone regurgitate the same tired theory

I'm not your research assistant. Google is your friend.

 

[SavetheRimBrake]

That’s an interesting way of saying “I don’t have any”

 

[TiGeo]

That’s an interesting way of saying “I don’t have any”

That's an interesting way of saying "I'm too lazy to look up this issue that I'm interested in learning more about that folks here are talking about that I think are wrong."

 

[cptbarkey]

That’s an interesting way of saying “I don’t have any”

do it yourself. Buy two engines. Pour some gas into oil and measure the viscosity. Do a control. See which engine explodes first. Or, read what others have already done. Good luck ace.

 

[TiGeo]

That’s an interesting way of saying “I don’t have any”

So what is your take then, specifically? What is you threshold for too much fuel in your oil, if you have one?

Here's mine. I've done lots of UOAs on my fleet and have some fuel dilution (BS so not that accurate) at low levels in my 3 DI vehicles - I'm sure if I ran the Atlas and Sportwagen samples at a different lab they would come back in the 3-5% range but of course, I haven't so that is a hunch. I have set my OCIs at the popular ~5K miles on those vehicles (GSW is tracked/boosted/>2x stock power level and Atlas is all short tripped for the most part) - I see no reason to push them out to 10K/once a year for a few more bucks when I know there is some elevated level of fuel in their oil. What am I losing? Nothing but the few runs to Starbucks worth of supplies. I am not a sky is falling oil changer or fuel paranoid - I took my '00 MK4 Jetta up to 220K/14 years on primiarily 10K M1 0W40 changes. That car wasn't DI or turbo and saw mostly highway driving. The car was falling apart inside and I got 100% of my $16K I paid for it new when I sold it.

My recommendation for folks worried about fuel in their oil is to send a sample to a lab that uses a direct GC measure of the fuel % and assess the risk themselves. Fuel dilutes the viscosity and is a solvent...this isn't good for lubrication which should be "common sense" and is substantiated in technical tribology papers. Gas also tends to "burn off" if you get the oil at operating temp (not short trips) which will help reduce issues. Normal background (to me at least) 1-2% fuel in modern DI engines isn't something I'd worry about or start moving oil up a grade as many here do. 5% is starting to get significant in my eyes. Honda clearly thought it was enough of an issue to revise their ECUs to attempt to reduce it on the 1.5s.

Here's one:

Fuel-Lubricant Interactions: Critical Review of Recent Work

A critical review of recent work on fuel lubricant interactions is undertaken. The work focusses on liquid fuels used in diesel and gasoline vehicles. The amount of fuel that contaminates the lubricant depends on driving conditions, engine design, fuel type, and lubricant type. When fuel...

www.mdpi.com

 

[DavidJones]

I suspect some part of the answer is vehicle/oil specific. A friend had a 2016 F150 with the 2.7 Ecoboost. I believe it is considered a "diluter". Pat runs parts all around the southeast for an industrial supplier and in around 6 years ran up 465,000 miles on his truck and only got rid of it because the transmission was going out. When Pat bought the truck, I asked him what engine it had and he was unsure. I believe his answer was something like "it's got a v6". I had a similar truck, so I kept up with how his truck did, knowing it was going to run up the miles and probably not get any extra maintenance. 10K oil changes with Motorcraft semi/syn. If fuel dilution was going to kill an engine, this one should have died an early death. No engine issues.

 

[TiGeo]

I suspect some part of the answer is vehicle/oil specific. A friend had a 2016 F150 with the 2.7 Ecoboost. I believe it is considered a "diluter". Pat runs parts all around the southeast for an industrial supplier and in around 6 years ran up 465,000 miles on his truck and only got rid of it because the transmission was going out. When Pat bought the truck, I asked him what engine it had and he was unsure. I believe his answer was something like "it's got a v6". I had a similar truck, so I kept up with how his truck did, knowing it was going to run up the miles and probably not get any extra maintenance. 10K oil changes with Motorcraft semi/syn. If fuel dilution was going to kill an engine, this one should have died an early death. No engine issues.

That's because he is not doing short trips. His UOAs would likely show low/background levels of fuel. All highway driving promotes higher oil temps and any gas getting by the rings is evaporating into the crankcase PCV. You can't compare this one to a vehicle in mixed or mainly short-trip/around town use.

 

[DavidJones]

That's because he is not doing short trips. His UOAs would likely show low/background levels of fuel. All highway driving promotes higher oil temps and any gas getting by the rings is evaporating into the crankcase PCV. You can't compare this one to a vehicle in mixed or mainly short-trip/around town use.

Then add "situation" to "vehicle/oil specific" reply.

 

[wemay]

I used to argue that fuel dilution wasn't a big deal if the UOA showed low wear. But after years of seeing increased consumption, drive train issues etc., across the board with all makes and models using GDI only fuel delivery, you can see how the slow creep, long-term results of dilution issues arise.

 

[Nuclear_42]

I'd like to add a new variant to this discussion. So 4-5% is manageable as long as you use a quality synthetic that maintains viscosity 3-5k miles. Now what's the effect of 4-5% plus on the engine seals/ gaskets overtime. Not many have talked about that. Most likely the engine designers had this a mind. However that's why I change the oil after 3k miles and 5% dilution. We need more data and input on this subject. If you can go as far as 8-10% dilution with perfect UOA why not but the seals/ gasket issue is holding me back.

 

[Opelman]

According to some of the more questionable members' recommendations, it's like you were doing an in-service engine flush!

You know, those engines were always rather clean when we pulled the valve cover to replace injector pucks, high pressure oil rail o rings, engine brake solenoid o rings and so on. The exhaust system would get an anti freeze flush too when the egr coolers failed. Must be why these vehicles come with a Cummins engine now.

 

[kschachn]

I'd like to add a new variant to this discussion. So 4-5% is manageable as long as you use a quality synthetic that maintains viscosity 3-5k miles. Now what's the effect of 4-5% plus on the engine seals/ gaskets overtime. Not many have talked about that. Most likely the engine designers had this a mind. However that's why I change the oil after 3k miles and 5% dilution. We need more data and input on this subject. If you can go as far as 8-10% dilution with perfect UOA why not but the seals/ gasket issue is holding me back.

How does a synthetic oil better resist the physics of dilution by a lower viscosity fluid?

 

[Nuclear_42]

How does a synthetic oil better resist the physics of dilution by a lower viscosity fluid?

I don't think I understand your question. There's plenty of quality synthetic motor oils that retain their viscosity spec after a good run in a DI or Turbo vehicle. Some brands simply shear grades.

 

[nicholas]

Also cold weather short tripping.
Our port Honda gets really gassy after 1-2months of winter use.

 

[kschachn]

I don't think I understand your question. There's plenty of quality synthetic motor oils that retain their viscosity spec after a good run in a DI or Turbo vehicle. Some brands simply shear grades.

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.

 

[DirectRejection]

Can you explain this. My small brain is having trouble understanding why starting with a thinner starting point would be better for DI. Not a thick / thin debate - just trying to understand?

It cannot help but be another0 thick / thin debate. That does not prevent the debate from being intelligent for once.

We know what the predominate BITOG answer is. Thicker oil and more frequent oil changes, with "faith in physics" are the answer.

I choose to endeavor to be precise and modern. Let's get past the "dipstick freakout."

Everyone should have a close look at the superb article TiGeo posted. There is beauty in the details. There are a variety of factors involved.

I will follow up later. Gotta go. Work deadlines.

 

[kschachn]

It cannot help but be another0 thick / thin debate. That does not prevent the debate from being intelligent for once.

We know what the predominate BITOG answer is. Thicker oil and more frequent oil changes, with "faith in physics" are the answer.

I choose to endeavor to be precise and modern. Let's get past the "dipstick freakout."

Everyone should have a close look at the superb article TiGeo posted. There is beauty in the details. There are a variety of factors involved.

I will follow up later. Gotta go. Work deadlines.

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".