I own a M6 2013 Convertible (V8 twin turbo), i bought it with 13k miles on it still under warranty and service, back in 2015. Ever since i got it i had to add 1 quart of oil every 350 miles, and i was told by the bmw service team that it was O.K. it is within their normal as it keeps driving the oil gets thinner and burn faster. so i first believed that bs but now that i drive my car daily its a pain to go for a top off almost weekly. Today was the third time i brought in my car for service complaining on excessive oil consumption, they checked for everything no leaking no anything abnormal. They said is OK to add 2 quarts of oil every 750 miles(it seems like they dont want to see me there that often). Now, I dont drive it aggressively or even on sport mode, it has now 43k miles in it. In 2017 i bought the extended warranty for an extra 2 more years. The warranty is over in June. I dont know what to do. any advises will be highly appreciated.