[oil pan 4]

Eco mode and oil changes.
Hyundai oil change intervals for the hybrid sonata is 7,000 miles and uses 5w-20 oil.
If I run eco mode all the time, especially in winter the ecu constantly shuts off the ICE and never gets up to full temperature. That cuts my oil change I interval to 3,000 to 3,600 miles. The oil get loaded down with fuel, thins the oil wears the engine faster, also increases possibly of slug build up running cool, fuel soaked and wet.

For summer I have the problem sorted, just driving in eco mode I was getting about 5,000 miles on an oil change. Now I get full 6,000 to 7,000 mile oil changes no problem. My solution is run it in sport mode occasionally on the highway, only loses about 2mpg in the summer. Goes from 40mpg down to 38mpg. Then when I get to town the battery is fully charged and put it in eco mode and that pretty much makes up for the 2mpg I lost on the highway.
I still see some fuel going into the oil. So my solution is fill the oil up just past the low mark when I do an oil change, run that oil for around 3,000 miles, then fill it the rest of the way with 20w-50 oil that keeps the viscosity where it needs to be through 7,000 miles even with 1 to 2% fuel in oil.

Winter is much more of a problem. Initially I was just changing the oil when I could strongly smell fuel, about 3%, at 3,000 to 3,600 miles. I tried the just past low oil change, then fill to full at 2,000 with 10w-30 oil, it wasn't thic enough to make a difference.
Between running sport mode as much as possible, it's my wife's car, so when I drive it and adding 20w-50 oil around 2,500 to 3,000 miles.
Now I get 5,000 to 7,000 on the winter oil change, depends on how much highway driving and I change it when I smell strong fuel smell.
I see up to 4 less mpg in sport mode in the winter driving in town and 2 less on the highway.

How do I know what the viscosity is and how much fuel is in the oil?
Testing.