If Your Door is in Good Shape - I would use the Wax ..
They also make a Wax Similar - Land Rover has been using it for Decades
Two Different Types _ 1 Type Flows very Slowly forever .
Other Type Flows then Hardens down in all the Seams and Welds - to Keep Out
O2 and Water ..
This Type of Wax - will do other Things for Your Doors LOL :
http://www.waxcenter.com/
Land Rovers :
http://www.waxoilme.co.uk/?page_id=4
Buy It Here in Spray Can
Dinitrol Range - RC 900 Rust Converter goes about 8 times Deeper then Others .. Video's on Line . .
Then there is the Home Made Version - Maritime Solution .
2 1/2 quarts turpentine
12 oz. beeswax / candle wax
1 quart light machine oil
With a cheese shredder, cut the wax into the turpentine, stir until the wax has dissolved, (takes a long time; you can use very low heat (a warm room) to aid but be careful) and thin with the machine oil to a brushable / sprayable consistency. Apply liberally. You can use a hand spray bottle to get into closed-off sections if you have a small access hole.
Land Rover - Swedes Volvo's : Spray Type
http://www.roversnorth.com/ProductDe...006&type=0&eq=