Excessive oil use and Smell through Vent

Oil leak on the left side, I cleaned it before and it has very slowly come back, I was told that the bolts down there are tighten enough so oil is coming through.

The smell started coming through after taking it to a mechanic and he did a standard service on it.

The smell is intermittent maybe happening once every few days and only smelt for a split second before disappearing again.

I have driven it 2000km and it is now needing a refuel on oil, dont know if thats normal