When time permits... Please list your Mileage and consider changing the Fuel Contaminated Motor Oil and Oil Filter over to Mobil1 5W-30 (or better yet for Cold Weather ...Mobil1 0W-30) and a New Mobil1 or K&N Oil Filter as soon as you can as the lubricity will have been effectively 'watered down' enough to cause excessive engine wear. Depending upon how long you've had to run the Truck under the present problem conditions... excess amounts of unburned Gasoline can also ruin your Catalytic Converter.
The fact that so much Gasoline has migrated into the Oil Pan enough to actually raise the Oil Volume and Level strongly indicates the engine may be suffering from having the Low "Squeeze"-Pressure Top and Second Compression Rings becoming
"Carbon Welded" deep inside of the Ring Grooves and cover the Piston Heads and Upper Cylinder Head and Valve Seats which have probably become quite choked up with Carbon Deposits over time.
If present... the artifacts of having Stuck Rings invite very excessive Blow-By and Low Compression problems...hence the presence of a lot of Unburned Fuel 'sneaking' around the Pistons. There are quite a few GMTN Threads that cover treating the Combustion Chambers and Rings of the Vortec I-6 and in this case, the 5.3L V8 Engines using the ACDelco TEC (Foaming Top Engine Cleaner) to very effectively remove any excess Carbon Deposits and improve your Compression and Fuel Economy. The ACDelco TEC is available here... in the Can as a Pure Liquid and also as a Foam Spray which may be easier to use on a V8 Engine. Having Two Cans of this stuff will guarantee achieving a thorough dosing for both V8 Engine Cylinder Banks:
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