The 15 and 30 K maintenance is mostly "check this, check that" and repair/replace as necessary in addition to fluid changes and filter changes (air filter typically every 30K, fuel filter 30-60K depending on model and year). Fluid changes are very important and typically have the following schedule on 80s/90s vintage Mercs.

Engine oil - every six months or 7500 miles
Transmission - every 30K miles
Coolant - every three years, regardless of miles.
Brake fluid - every two years, regardless of miles

Lack of reasonable fluid interval changes is likely to lead to premature problems on these systems.

The owners packet should have a maintenance booklet, and it has provision to document all the maintenance events including the time dependent fluid changes.

Duke