What maintenance checks should I do on my Audi 80 engine?

I recently bought an Audi 80 and want to make sure I'm taking proper care of the engine. What specific maintenance checks should I do to keep it running smoothly and avoid any costly repairs?

Regularly check the oil level and quality to ensure proper lubrication of the engine. Also, change the oil and oil filter at least every 5,000 miles.

Inspect the air filter and replace it when it gets dirty to ensure proper airflow and fuel efficiency.

Check all belts and hoses for signs of wear and tear, and replace them if necessary.