Fuel dilution is definitely still a thing, there are multiple threads on it, in fact there's a thread adjacent to this one on it where a guy is complaining about 13% fuel in his Honda 1.5L engine, which is notorious for fuel dilution.Motor oil does not become thinner as the miles accumulate on it. It did back in the days of carburetors when we had cylinder dilution caused by the inefficiency if a carburetor. Today's cars have fuel injection systems and cylinder dilution is a thing of the past. Injection systems measure the fuel delivery so precisely that it simply doesn't exist. Motor oil actually becomes thicker as time and miles accumulate as the lightest molecules "boil off" in dino oils. Synthetic oil is "built" with uniform molecules and doesn't experience the "boil off".
And if one ran out of corn oil, the 3800s likely will run fine on bacon fat.As long as you got oil pressure I don't think that engine cares. The 3.8 / 3800s just needed some kind of oil in them. They aren't stressed out, the timing chains are short, and they have a decent oiling system. The Supercharged ones at least running synthetic is advisable.
That is what I've picked up after owning a few of them, and friends owning them in different flavors. We would joke they would run on corn oil if you tried.