I would highly doubt any problems have manifested yet. Fuel diluting the oil causes excessive engine wear which is progressive and damaging over time. I suspect that well this may not cause an error code/engine light, the problem may be identifiable through advanced diagnostics.
Someone over in one of the Facebook groups claimed they had the catalytic converter go bad and replaced from this issue. It makes sense and could be the cause of worsening fuel mileage? Also, on the Facebook groups, I have seen 3 trucks that had the engine replaced, though the exact cause wasn't stated. I believe they were posted by a Ford mechanic and showed the truck up on a hoist with the engine on the ground as I guess that is the easiest approach for replacing the engine. i believe he claimed the issue for one of them was an "extended" oil change interval. Who knows, but there's no way the engine will last as long as it normally would, if it has substantial fuel dilution.
Two things are at issue here.
MotoWojo lives in Wisconsin. A significant drop in MPG during a Wisconsin winter is common. I experience the same decrease in my Ranger and Fusion here in Minnesota.
I experience at least a 2MPG drop with the winter blend. I've experienced this with a number of different vehicles! Winter blend sucks!!
This is the second winter I have had my truck as I bought it new on April 3rd. 2019. My worst tank, mpg wise, thru the first ~18,000 miles was 19.4 mpg (hand calculated). My best tank was 23.9 mpg during the summer of 2019 and I mostly averaged between 22-23 in the summer and that went down a couple in winter. In the last 5,000+ miles, my best tank was 18.1 mpg with most tanks between 16.0-17.5 mpg. My commute to work is exactly the same and I set my cruise at the same speed I have since I bought it new. So, I am seeing an additional 2-3mpg loss even taking winter into account. My 50 mile round trip commute, 5 days a week, is ~90+% interstate. I would guess that over the life of my truck, 90+% highway, less than 10% local. I do occasionally pull a trailer, but it is just my dirt bikes and is very light (Kendon Dual Stand Up).
Colder temps? It's a lot colder here this winter than last. I think the mpg's drop with the temps an the remote starts go up.
C'mon now, September, October, November, December, were all warmer than usual and I was seeing significant mpg loss during those months. Granted, the past couple weeks have been brutal, but my mpg issue really became apparent back in September. Fuel in oil issue started back in March of 2019. Also, for what it's worth, my truck lives in a heated garage (I keep it at 55 degrees) when I am at home. I believe I have used the remote start a total of 4 times since my truck was new and 2 of those times were in the past week.
I think you are mostly right. Ford surely understands what is going on for us Ranger owners that are seeing moderate oil dilution, like me, where the last two Blackstone reports showed 3.8% and 3.3%. But I don't know if they know what the exact problem is with the more extreme/isolated cases like MotWojo's Ranger. I sure hope the field engineer examination of his Ranger results in a solution for him.
I'm sorry to keep reading that this is still unresolved.
