engine flush/oil change

[japimport]

hi there i have a c200 sport 95 with 118,000 miles on her my car rattles on start up for about 2 seconds then its gone,iwas told today that its like that because the oil has dropped to the bottom of engine over night it rattles til itsback up top, and also on idle the car is a bit shaky too,and on tick over its tapping so i need to know if doing an engine flush would sorrt it out and whats the right oil or my car ive put castol magnetic in it about a month ago is this ok or am i( just panicking) its my first merc and i want it to last thanks thomas i hope i made some sense there

 

[oigle]

I imagine your problems are not related. The engine rattle is no doubt due to a worn timing chain that requires oil pressure to activate the tensioner and take up the slack - normal for such a mileage.
Rough idle is a tuning problem - get it seen to.
Ticking at idle is probably an incorrectly adjusted valve lash or tappet. All valve clearances should be adjusted every 100000 miles at least. Maybe yours weren't done.