Fuel in the oil

A month ago I pulled out on the highway and pushed the truck a little. About 1/2 mile down the road it began rolling smoke out the back but not exhaust, it was burning oil. I stopped and looked under the truck and down the passenger side was coated with oil. Just enough to burn on the exhaust pipe. It stopped and I continued driving the truck. Checked the oil and level looked fine.
Week later I drove about 20 miles and when I went to turn off the highway the truck died. I cranked it a bit and it started. Ran home and turned into my driveway it died again but would not start this time and no oil pressure.
Cold here in Ohio so next morning I tried the truck and it tried to start a couple of times and then it fired up.
Checked the ICP, pulled the IPR Valve and cleaned it and replaced the screen, old one was fine. Checked the wiring for chaffing, checked the FICM. All checked out and no codes.
Truck started and ran fine but noticed a real slight ruff idle. Drove the truck for about 50 miles and did fine. Took it out last weekend and after 25 miles turned into a driveway and truck died and wouldn't start. Towed home.
Sat for two days and tried to start twice and on third crank it fired up and ran good.
Here is what I have so far. I have always changed the oil on schedule and even so, minutes after running the engine for first time the oil is dark. When I checked the oil after this tow home it was almost clear and didn't smell correct.
I believe that a month ago something gave loose when all the oil burnt and now there is fuel in the oil and it is thick enough when cold to start but loses oil pressure when hot and quits.
How does fuel get in the oil? Are we talking bad O-ringes on the injectors and if so which ones.
Thanks

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As stated on the Org forum ......

An upper injector o-ring is the most common way.

That said, it can occur from an internal o-ring (the "body o-ring") in the injector failing as well. This just isn't as common as the external upper o-ring, IMO anyway.

Lastly, an injector can dump excess fuel in a cylinder (worn plunger and/or barrel) and from there it can get past the rings; or the burn efficiency can be poor due to nozzle wear or from a cold engine, or from excessive idling Any fuel not properly atomized and combusted can get past the rings through cylinder washing. Typically this doesn't result in a large amount of fuel in the oil, but if it did, you would see it from the tailpipe (white smoke) - especially on cold start-ups!