How do I know if my Audi A4 needs a coolant flush?

I am not familiar with car maintenance and am wondering if there are any tell-tale signs that my Audi A4 requires a coolant flush. Any advice would be appreciated.

If you notice that your engine is overheating or there is a decrease in performance, it is likely due to old or contaminated coolant. It's important to schedule a coolant flush to prevent any further damage to your Audi A4.

Another sign that your coolant needs to be changed is seeing a milky or oily substance in your coolant reservoir. This could indicate a leak or contamination and should be addressed by a mechanic immediately.

If your coolant levels consistently seem to be low, it could be a sign that your system is leaking. It is important to address this issue as it can lead to overheating and potential engine damage.