What is the best way to maintain an Audi 80's engine?

I recently purchased an old Audi 80 and I want to make sure I properly maintain the engine to ensure its longevity. What steps should I take to maintain the engine? Are there any specific products or techniques I should use?

Regularly change the oil and oil filter to keep the engine running smoothly. It's recommended to change the oil every 3,000 miles or every 3 months.

Check and replace the air filter if necessary to keep the engine's air intake clean and free of debris.