Oil keep getting in my coolant...

What is your question?

I have replaced the radiator and had flushed twice but the same result. The car is not overheating, there is no white smoke coming from tail pipe and my engine oil dip stick is clean. I have been told its not the trans cooler. The last mechanic said it might be coming from the timing cover and will need to be reseal but at the cost of $2400.00 but cant confirm it will solve my issue. The car is not worth that much although its in excellent condition. Could you please advise on what the issue might be? I don't think its the gasket.