What should I do when my Audi 80's engine overheats?

I have a 1990 Audi 80. Recently, while driving on the highway, the engine temperature suddenly shot up in the red zone. I pulled over and let the engine cool down before adding coolant. However, the issue keeps happening during long drives. What could be the problem and how can I fix it?

It sounds like your Audi 80 may have a faulty thermostat or a leak in the cooling system. It's important to address this issue as soon as possible to avoid any potential damage to your engine. I recommend taking your car to a trusted mechanic to diagnose and fix the issue. Be sure to mention the specific symptoms and when they occur.