Coolant and Engine oil mixed problem 2007 A8

I have 2007 A8 with 100,000 miles and I have the problem, coolant and engine oil mixed.

I realized coolant level decreased after I filled it up and I was shocked because engine oil looked like jam when I changed an engine oil and filter.



The coolant is decreased because coolant and engine oil mixed.

Is this a common issue for Audi?

Anyone had same issue and have a solution?



Please help me.