2,4 T is like a hole, why?

Hy people, now I’ve had an august my V70 2.4T Bj. 11/99 with 135000km at first he needed so 12 -12.5l on 100km then he got an oil change with 0/40er and a ceramic accessory when he then got a sports air filter insert (K&N) he suddenly needed more instead of less…?! was with the past cars mostly so that they needed a tiny piece less, whistle on the performance so, since the 0/40er oil was too thin he got a 10/40er as it is in the direction, a fine then he needed again more now I new candles (original) pure, and you will not believe it by now I am at 14,5-15 l mixed traffic, and tret him as well as not at all. if I think I had a 300E mercedes with made Carlsson machine, therefore mer cylinder and more PS and so look 13 years older than the V70 and that needed in the city 10liter and on the train is no longer enough for you?