Partailly compressed air in a 12:1 engine might be at 400-600 degrees. Some manufacturers/designs inject a lean mixture early in the up stroke then puff a bit more fuel near the ignition event to create a rich pocket near the ignitor creating a stratified charge (and lower the misfire count).
I'm on my 2nd Hyundai with D.I.--the first was a 2.0L turbo DI, and my current one is a 2.4L NA-- oil analysis on both indicated that neither had unusually high amounts of fuel in the oil (@4000 mile OCIs). Despite various comments to the contrary, Hyundai's seem to have a decent implementation of D.I. The mileage / power on the 2.0 TDI was amazing (wish I'd kept it, but my son needed a vehicle, so he ended up with it). The 2.4 D.I. is OK, but power / mileage isn't nearly as good as the TDI. My next one will be another TDI I think.
@Jetronic. . . my use of TDI may be misleading as I know that VW uses that acronym for their Turbo Diesel Injection. . . . my Hyundai's were / are both gas.
I wouldn't attribute it to fuel dilution but something else.
With batch-fire, yes, with SEFI, the fuel is sprayed as the intake charge is being drawn into the cylinder, so there's a column of air moving down the intake port that the fuel is injected into, which is pretty much ideal for blending and creating that homogenous charge of air and fuel.
Use a good quality synthetic oil and change it around 4000 miles your engine will thank you.
Huh
Can you provide sources that make 5% fuel dilution acceptable ?
When I do that in my car's tailpipe at 137k miles, my finger comes out looking about as clean as your little finger did. Port injected, of course.
You have 2 different results, which appear to be from the same sample mileage (???). Can you explain? Did OAI just “forget” to report fuel on one of the 2 analyses?
I analysis, fuel dilution was just on another page I think. I don't remember how it printed.
I have a newer Ranger with GDI and belong to a few Ranger boards and groups. A number of people have mentioned the smell of gas in their oil or fuel dilution in the UOA but if you ask them some questions you find they they are invariably folks who do a lot of short trips and don't put on many miles. Me, my work commute is 20 miles each way and at least three days a week I run 15 miles down the Interstate to our other facility and back. Haven't got a UOA yet but I never smelled gas in the oil either or seen the oil level go UP like some people have.
I drive highway mostly 90% and my gas had 5% oil dilution as per UOA. And no, you will not necessarily be able to detect gas smell with your nose. Why dont you do some UOA instead of using your smell and telling urban tales about others doing short trips
DI engines should be less sensitive to valve overlap especially with fixed cam timing since the fuel injection can occure during the compression stroke. The late injection timing will also reduce the cylinder wall to fuel exposure.
