I have started losing about 1/2 to 3/4 qts. of oil every 1500 miles or so, around 2500 miles into my oil change. On average, I have to now add about a 1 1/2 qts. of oil between every change, which is done in 4500-5000 mile intervals. I use Mobil 1 5w-30 full synthetic, drive about 75 miles roundtrip to work via highway M-F, and live at 5500 ft altitude. I started driving the car one weekend a month on a 1400 mile roundtrip. I am at 133,500 miles. About 9 months ago, after noticing leaks in all the usual places, I replaced the VCG, OFHG, CCV, and did the vanos. No noticeable leaks at this time, anywhere.
My assumption at this point is that I must be burning oil. I am thinking the addition of the 1400 mile trips every month, supplemented with my daily driving has added some extra wear on the engine, allowing for oil to be burned, though the amount seems excessive. My spark plugs are not showing signs of excessive oil blow by, and there is no white smoke.
Is this just normal engine wear/time to replace piston rings or could I be missing something else?
Thanks for your input!!