Hello all, Looking for some help trying to find out what may be causing my oil consumption issues. any direction would be appreciated. My 2003 Yukon Denali 6.0 (209,000mi) had the rear main seal replaced about 10,000 miles ago because of leakage. I ran it awhile prior to the new seal. keeping an eye the oil level. I ran it down pretty low a couple times to the point where it barely read on the dipstick.. didn't use any specific oil brand as long as I kept it on the dipstick. Prior to seal change I had no oil usage issues. since the change I have been going thru a quart every 1300 mi on highway and 700 in town. I have no coolant in my oil or oil in coolant. The only oil I see is my cover gasket seeps minor oil...nothing even close to what I am using. no smoke out the exhaust on startup, hammering it down cold or hot. my oil pressure is 35-50psi depending on temp and rpms and I get 12-18 mpg. it runs great just a slight rough idle if you feel for it. Since seal change 5 months ago I have done the following on order -cleaned the PVC valve (light oil in it...no spring type) been there since I bought truck at 60,000mi -Compression test- all cylinders dry 180-190 w/oil 182-200. seems high...but consistent. first timer with new cheap gauge and 8 cranks. -new plugs & wires. some oil fouling but not gross. gonna try to match up pics of plugs I took back then with cylinders today -replaced original catalytic converter on left side only (p420 code) -changed intake gasket. felt slight stumble when sprayed carb cleaner around area. (knock sensor clean area between gaskets not oily) cleaned throttle body-all vac lines to it, fuel injectors, intake and path down to valve as best as I could with carb cleaner. had some caked on carbon/oil outside injector spray path . looks lot better now. just don't know where to look next. valve seals, gunked up rings, bad rings? could the main seal change gone wrong...that the timeframe it started....any ideas besides my engine on its way out.