(The Numerical Order of what follows is Irrelevant...The Hosing mentioned here is for the I6... so there will be a variation on WHERE the hoses enter or exit the Block to Intake Manifold...but the Principles are identical for your 5.3 V8...
If you Pull out your Oil Dipstick and you can smell gasoline fumes... then your piston rings have become worn enough to allow Gasoline Fumes into your oil pan...losing lubricity...and allowing the thinned down oil to pass the rings on all cylinders and be burned at a much fast rate.)
There are two, small reinforced rubber hoses fitted to this Atlas Engine that serve as the means to recycle Oily-Gassy Vapours created by the "Over-Pressure" made inside of this Engine:
(1) The Lower Crankcase can become over-pressurized due to the Cylinder Blow-By caused from the imperfect Sealing of the Pistons Rings. So these partially burned gasoline vapours right along with whatever oily mist that gets created by the violent action of the Rotating Assembly, Crankshaft, Rods and Pistons are picked up via a small, Rubber Elbow Hose on the outside of the engine via a spout in the block adjacent the centre underside right near the lower Intake manifold where the Rubber Elbowed Hose connects up to the Lower Intake manifold.
It is through that hose that internal Lower Engine Block air laden with Oily-Gassy fumes allows it to be sucked along the air stream coming through the Intake Manifold and thence passing through the Dual or Single Intake Valves of each Cylinder and then down inside each of the cylinders during every Intake Stroke ...to be added with the discreet injections of fuel and NA air and then burned (or re-burned) after the Compression and Power Strokes occur,
(2) The second area that can suffer with Oily-Gassy Fumes is directly under the Valve Cover(s) ...and under there is small, reinforced Rubber Hose that allows fumes from that location to be sucked out from under the Valve Cover(s)... back up inside of the Air Intake Plenum with the Air Stream and thence through the Throttle Body and it too gets handled in exactly the same manner mentioned in paragraph (1) .
The reason for all of this being done is to satisfy the demands of the EPA Clean Air Act and redirect these noxious, combustible and oily fumes back through the Intake Manifold and cause the Engine to Burn these vapours instead of dumping this Polluted Air out into the Environment. If you ever take off your Intake Manifold and look at all the Black Oil inside of the bottom where the manifold and gasket mate with the Intake side of the Engine Head(s)... you will see two of the four possible reasons why Oil Gets Consumed by this engine as a Normal Part of its Operations...just as
@hockeyman stressed in the above post that covers all of these (1-4)...including seepage around Valve Cover Gaskets and from the front and rear Crankshaft Seals.
(3) The third reason for this loss is that Oil under "sling" pressure is dousing the walls of each cylinder to lubricate and somewhat cool the Piston & Rings-to Cylinder Mating surfaces... and invariably a very small amount of the stuff remains stuck to the rings and the walls and it gets burned up in small amounts, right along with the combustible EFI Fuel Sprays, or by Carburettors or any other means of fuel delivery using the Natural Aspiration of Air.
There is no proper reference in TIME that is valid here as to how much sooner this happened... because it does not matter whether it takes you Six Months or Six Days to drive the 3,000 Miles between Oil Changes... The Engine will consume the same amount of Oil during BOTH circumstances... But realize that driving a GM Truck or an SUV filled with a bunch of kids asking you, "Are we there yet...?" every five minutes ...right along with Towing a hooked up 22' Trailer...will add additional stress on both the Engine...and The Driver... ;>)