The invention discloses self-priming coating composition based on a vinyl terpolymer, a monomeric or oligomeric alkoxy amino resin cross linker and a multi component combination of two or more resins selected from (a) oligomeric saturated polyester resin, (b) oligomeric unsaturated polyester resin dissolved in an unsaturated monomer with a free radical initiator (c) oligomeric bifunctional phenolic resole resin and (d) oligomeric epoxy resin (e) low molecular weight polyurethane resin and (f) short to medium oil alkyd resin, wherein said vinyl terpolymer is predominantly polyvinyl formal with polyvinyl alcohol and polyvinyl acetate as two other co-polymers. The composition can be applied as a clear coat or as a pigmented composition with addition of pigment on ferrous and non-ferrous metallic substrate and is particularly suitable for continuous coil coating lines for both dark and light colour metal coatings. The invention also concerns method of coating ferrous and non-ferrous metallic substrate by applying the said coating composition on a degreased but untreated surface and coated articles so produced.