I was on my way to my friend's in south Florida and the issue started on my first bathroom/fuel stop at 2 hours. I parked the car, went inside for the bathroom, started the car and moved to the pump, filled it up, and then it cranked for a bit longer before starting. I decided to just keep going. 2nd fuel stop, same series of events. Stopped, started, fueled, much longer cranking. I decided that was the last time I was shutting it off until I got to my friend's. I used the car a couple of times while there with no issues. Then on the way back, fueling up led to long cranking and got a solid CEL. P0496. I let it run the whole rest of the time.

I've made that 1460-mile round trip 3 times in the last 2 years in the SS. Solid all the way. Emissions garbage doesn't count as a real problem. 28.5 MPG this trip. Recent Blackstone Labs report shows high fuel in the oil. I think my short trip usage of the car most of the time is the cause. I don't drive out of my town in my SS very often and I work at home. It's in warmup a lot. No excessive wear metals otherwise. I'm thinking of getting the GMPP clutch and later a dyno tune. I've been running Trifecta for years and it's been great, but it's a canned tune and I can't remove cat warmup with HP Tuners.

 

With the evap purge failing and shorter trips on your UOA it's not surprising to see more fuel in the oil.

I've been through at least 3 purge valves, make sure you test the new one before installing, even if ac delco brand. There is a YouTube video (can't recall the channel) of how to test it and the one the guy pulls the the packaging fails (allows air to flow with no power as the normal state is closed)

 

Thanks for the tip. One other symptom while it was failing was it started sputtering while I was filling up. No CEL, so no misfire. Just a mixture problem I guess from sucking unmetered air through the gas tank opening.