Painting a 6 panelled moulded door

A wash down and rinse first wouldn't do any harm, then rub down with an abrasive (not too coarse)to provide a key a 'key' for undercoat, you're introducing a water based system on top of an oil based system so this is important. If unsure you might want to prime first with a high adhesion primer before undercoat and gloss.

Firstly, painting a six panelled door takes longer than the average door, so I would ask you to still consider using an old based paint, as there is a risk of the water based paint snagging when you come to paint the horizontal & vertical sections of the door, the benefit of oil is that you have a longer time to work with the paint on the door before it becomes touch dry. Oil based is also tougher & more resistant to wiping clean.