During the first 5000 miles, my 2016.5 Mazda CX-5 with 2.5 gas engine didn't use a drop of oil. But during the next 5000 miles with semi-synthetic oil, it used about 1/2 quart. When I did my last oil change at 10000 miles, I used Castrol Edge 0-20 fully synthetic oil. And it seems like it is going to use more this time. Tailpipes are clean, and no leaks. Is this normal, to use some oil between changes?