[dw1]

Engine oil degrades from sitting. It absorbs moisture and also gets a bit acidic. Change the oil immediately.

Also, it is probably too late for this, but one should be extremely careful starting a car that has sat for a very long period of time. The initial crank of the engine is moving the pistons in cylinders that have very little oil in them because it has drained out over time, causing excessive wear. The same with crankshaft bearings.

Also check for rusty break lines and fuel lines under the car (likely under a plastic panel). A little-known secret is that there really should have been a recall on several generations of c-class cars (W204 & later) for rusty brake & fuel lines.

Of course, also check the disk brake rotors (esp. the rears) because those have a tenancy to rust from sitting.

I've owned several generations of C-class cars and I do like them, but like any other car things do go wrong.