Fuel in oil. Discuss

[arghx7]

It's got fuel in the oil. So what? Your car is new and has a warranty. You think they didn't see fuel dilution in durability tests? Somebody at Ford thought the amount of dilution was acceptable for typical owners' use.

All you can do is trust them, or not trust them and change your oil more frequently.

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[greg hazlett]

These are the same people (Ford)who send the dirty oil back into your intake so........yeah.....

 

[Dirtleg]

It's got fuel in the oil. So what? Your car is new and has a warranty. You think they didn't see fuel dilution in durability tests? Somebody at Ford thought the amount of dilution was acceptable for typical owners' use.

All you can do is trust them, or not trust them and change your oil more frequently.

I'm sure your right about Fords knowledge of fuel dilution and what's acceptable. As such I'm not worried about reliability more I want to understand what exactly about DI causes this to happen. I've got time to research as it is. I

 

[5TAR5CR3AM]

These are the same people (Ford)who send the dirty oil back into your intake so........yeah.....

Not just ford... every manufacturer of engines that use a modern PCV system, which is like everyone. so.... yeah.... :headbonk: :lol:


Useless comment is.... well useless.

 

[greg hazlett]

Sadly you are correct...

 

[arghx7]

I'm sure your right about Fords knowledge of fuel dilution and what's acceptable. As such I'm not worried about reliability more I want to understand what exactly about DI causes this to happen. I've got time to research as it is. I

First, any boosted engine will have a higher quantity of fuel entering the combustion chamber to match the higher airflow. That automatically means more opportunity for fuel dilution.

Now, one of the major causes of oil dilution in a DI engine is the spray targeting and injection timing. The 2.3 Ecoboost is a side injection engine, while the 1.6 and 1.0 Ecoboost are central injection engines. Side injection engines architecture include the follow advantages:

1. More space in the cylinder head to package larger intake valves
2. Lower temperatures at the injector tip
3. In some cases easier manufacturability
4. Less chance of wetting the intake valve

Now check out this image from the sticky thread:

See how the injector sprays and the fuel plumes move toward the bore wall? That is more likely to happen on a side injection engine. But here's the thing - it depends on the injection timing. Tuning injection timing on a side DI engine involves tradeoffs between the spray hitting the piston top (too early or too late), the spray hitting the bore wall (too late, and sometimes too early if it reflects off the piston crown), and the spray not having enough time to develop a good mixture (late injection timing). It also depends on the design of the intake port and combustion chamber, as that will direct the airflow and could reduce or increase wetting & oil dilution. Any port & chamber has a tradeoff between promoting mixing in the combustion chamber/reducing knock and promoting good airflow.

Now the other type of system is central DI, like the 1.6 liter Ecoboost. Here's an image of a central DI combustion chamber:

The central DI engine has the following characteristics (plus others):

1. Less space in the cylinder head to package larger intake valves, making high performance and high flow heads more difficult
2. Higher temperatures at the injector tip, increasing durability concerns
3. With the right spray targeting, less chance of spraying the bore wall, which can dilute the oil
4. With the right type of injector, ability to form a mixture by relying primarily on spray characteristics - see the current Mercedes engines with A-cone piezo injectors and the old N54 BMW engines.
5. With the right type of spray targeting and injection timing, less chance of spraying the piston top, which can cause the nasty black smoke you see on DI engines
6. Higher tendency for spray to hit the intake valves, with the right injection timing.

That doesn't mean "side injection engines always have more oil dilution than central injection engines," but those are fundamental characteristics of the two systems.

So if you have a turbo DI engine, the turbo means more fuel in the individual cylinder and the DI means the fuel is more likely to stick to something you don't want it to stick to, generally speaking.

 

[greg hazlett]

Good post!

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