What's the carbon deposits in the first filter from? Did you use any kind of engine cleaner on that run? Wouldn't think it gets that cold in TX to be short trip carbon in very cold weather.
No cold short trips during either of these oci, even though we do have a place in the CO mtns. But the vehicle hasn't been there for a few winters. And when we go in the winter its only there for a week or two.
Yes, I did try a product called "PolyDyn TX7" for that 3/21 to 3/22 oci. Its not known as an engine cleaner and that wasn't why I used it. The oil analysis didn't show anything different at the end of that oci, so I figured it was just a wast of $20.
No additives in the 3/22 to 9/22 Amsoil oci.
I save my old filter elements for occasions like this.
We've owned the vehicle for almost 4 yrs. Bought it w/130k miles. Unknown mx history. I immediately determined is was burning and leaking 2 oz/100 miles. I updated driverside valve cover with GMs new and improved one, replaced the rear main seal, oil pan gasket, changed the oil pump pickup o-ring, and added a catch can. The inside of the engine has got a fair amount of carbon on everything that wasn't removed or replaced.
The piston oil control rings were stuck. So while I was doing this mx and had the spark plugs out, I did a weekend long piston and combustion chamber soak by squirting Gunk brand Motor Medic into each cylinder and occasionally moving the crank back and forth.
The engine hasn't leaked since and now consumes only 1/2 qt/6k miles.
In the summer of 2020, I added an engine oil bypass filter setup (Amsoil EaBP90), increased the engine sump capacity from 6 qts to10.5 qts, removed the oem 195*f thermostat for a 180*f, installed a small engine oil cooler, and at the 3/22 oil change started running 0w-20 wt oil.
My theory is: because it's an all-aluminum engine it needs extra help dissipating the heat. Thus, the mods listed above.