Painting question non woodworking

[Randy C]

I am repainting my fathers front door and shutters. The door is a metal door and the shutters are vinyl. The front of the house gets heavy sun.

Can anyone tell me the best primer and paint type that I should get. The guy at Lowes said I should use Rustoleum metal primer which is oil based. The previous paint on the door was oil based and the sun made the paint crack badly. 

Should I use an oil based primer or something else? I would like to use the same paint and primer for both the metal door and the vinyl shutters. What type paint?

Thanks

[Phil Thien]

The instructions that came with my metal door said to NOT use oil-based products over the top for the factory paint, that if I wanted to repaint to use a water-based product.

[fredhargis]

I would say a 100% acrylic exterior paint for the door, which follows what Phil said, but I can't imagine it sticking to vinyl.

[Cooler]

I took my door off the hinges, laid it flat and sprayed it with Rustoleum primer  and Rustoleum black gloss.  By laying it flat I eliminated any possible runs and I laid down a heavy coat that self-leveled to a mirror finish.  

Left in the sun it dried sufficiently to put it back up late afternoon.  But don't install it too quickly or it will stick to the door jambs.

It is only one year so I cannot speak for the longevity, but black finishes tend to be UV resistant.