My 2000 C280, 60m, is probably overdue for a plug change. Is this procedure pretty routine save for the cost of 12 plugs? Also I been reading that there is a potential of frozen plugs with this engine and that anti-seize is recommended with a change. Is it ever appropriate to spray a penetrating fluid like WD40 or Liquid Wrench down in the spark plug bore before trying to break them loose?

Thanks,

glenmore
2000 C280
1991 300CE
1990 LS400