- Feb 17, 2010
When I look at used engine oil reports that folks post from their GDI vehicles, it's evident that fuel dilution continues to increase with mileage. And that's one of the main reasons it's recommended that GDI owners change oil by about 5K miles or so, regardless of what the owner's manual or engine's oil change indicator says.
I guess it doesn't make sense to me that just a single hour of highway driving wouldn't cook all the gasoline out of the engine oil, reducing the dilution amount to zero each time you made that one hour highway trip. Heck... gasoline has a flash point of something like -45˚ F. But it somehow manages to stay in the oil. Interesting...
Gasoline is a cocktail of various chemicals, some of which have boiling points of 250-450 degrees F. Your oil doesn't get hot enough to fully remove all of these chemicals.