girlfriends 13 malibu 2.5 LS a DI engine was steadily consuming MORE oil about 1500 a qt with mobil I 10-30 so i tried lubro-moly 5-40 + its down a qt in a thousand miles!! i had used thicker oils in the past for thirsty engines but Pa winters requires at least a 10-30. her car drank the dexos spec xx-20 oil when newer. i was thinking a 15-40 but would it flow enough in colder weather, + even considering Redline REAL synthetic as it thickens LESS than typical FAKE group III "synthetics"