Had a problem with the heating in my car. No heat at all when car idling. Over 2500 rpm some heat. Mechanic found gases in my coolant. Head cylinder needed to be shave and the head gasket replaced. Job done. Two weeks later my engine oil light comes on. I top up the engine oil. Three days later sure enough the engine oil light comes on as well as the service engine light. I immediately turn the engine off. Took car back to the mechanic who performed the previous service. I figured that the mechanic when taking the engine apart and putting it back together did something wrong. He could not find any oil leaks or solution to problem. Told to fill up the engine oil and check the level every morning. I did this for 5 days and noticed the oil level falling drastically. Please help. Desperate.