Audi Oil burning
 

Hi
I have Audi A5 2010 , where I am having oil burning issue I had piston ring replaced but still MMI display shows no oil level it start with oil level currenty not available and then show no or less than min oil level.
Also after piston ring changed I spotted oil leakage near timmimg belt cover very very small.
Car is heating when left idle or at traffic signal with AC blowing warm air.
Any advise or help please.