so heres my story. bought my aveo a month ago. 06 Aveo LS

so, since i bought it i noticed that the engine would get pretty loud at around 45-48mph. coincidentally i can feel a gear switch happening around that range. still does the same noise even if i put it on hold. thought it was the oil, since it was dirty, so i changed it and put some engine repair additive.

still the same noise. it bothers me.

I dont know if the timing belt could be it, since i've heard that aveos' timing belts go around 60k-70k, and mine is at 73k currently, and i dont know if it has had the timing belt changed.

but aside from this the car runs excellent before and after 45-48mph.