I had some experience with this in the last 6 months. I put a oil seperator/filter on the PCV system of my '87 Buick Grand National sometime last summer. Everything seemed good for a while. I was getting about an ounce or two of oil in the collector every 1,000 miles. It was nice to know that crud wasn't coating the intake system and being burned in the cylinders like it had been. Then came winter temps.
I checked the PCV collector with about 40 miles on a recent oil change last November. There was probably close to 2oz of raw gasoline in there
I thought my engine was hosed. So I watched it over the cold winter months on the rare, dry days that I drove it. It was the same thing as far as what was being collected. Obviously I was super worried but after researching on here and other enthusiast boards for my particular car, I noticed this seemed like it may very well be typical for cold weather. Difference being that most people aren't able to see the amount of activity going on with blow by and the PCV system without a collector/filter.
During the winter, on warm days(50f+), there was just trace amounts of gasoline in there and now that it's even warmer the gas collected is gone completely.
Keep in mind, the car always drove and idled normally, doesn't use any noticeable amount of oil at all, the oil level never showed going up or down and the oil still looks nearly new on the dipstick. As a note, this car has darkened the oil faster than other cars I've had. Usually it's fairly dark by 1,500 miles.
I also had a thermostat that was apparently running colder than it should. It's a 180* thermostat but when I put the car on the computer in past winters it would show temps in the 150's In the summer it always ran where it should so with the 500 or so miles I put on it in the winter I didn't bother changing the stat. I did that last week
so I'll see if there's any improvement with the blow by next winter.
Anyway, this was an eye opening experience regarding blow by, fuel dillution and how active a PCV system can be in cold temps etc.