The old Mercedes diesels are very reliable. During the following video, you have an example from reality.
A Mercedes W124 300 Diesel, made in 1986 and used as a taxi has, travelled almost 1,4 million km. On the dashboard, it shows 380,000 km because it has rolled over once.
This could be ordinary news for a diesel Mercedes which is famous for its reliability. But the sensational in this news is that, after the car was put away in 2003, due to rust and because the engine had been worn (it didn’t start during winters and it smoked really bad). it starts again 7 years later!
The start was not easy, because the owner had lost the key, so he had to connect the glow plugs and the starter with a wire.