Customs Treating rust

Once again I turn to this group for guidance. A friend has brought me a panel from an old truck that has rust pitting (pic attached). I have been using rust removal discs and wire wheel to remove the rust with good success. However in the deeper pits rust remains. The owner says he plans to keep the truck for at least a few years. New panels are not an option. So the questions are:
1. Remove or neutralize the rust: sandblasting, electrolytic dipping, rust removal disc/wire wheel, or other method.
2. Coating following rust removal: zinc chromate, epoxy sealer such as POR-15, epoxy primer, or other.
3. Smoothing out pits: icing, polyester filler, or other.

Any guidance would be appreciated. Thanks

 

Well, I don't know if it's the right way but I did this to my Pickup:
paint rust stripper disk on my 4.5" grinders followed by Ospho. Let it dry and use a red pad to prep for epoxy primer, Be sure to scrub off and white spots from the ospho.
When the epoxy is dry, use glaze ( good 2k, not the old lacquer stuff) on the pits, sand with 120 and hit with filler primer.

 

Ditto on OSPHO, as Ken said. For a frame, after OSPHO, we just use aluminum paint, and the color coat after.

 

Ospho and use zinc chromate primer?

 

Mol***es removes all the rust in the pits.
Epoxy primer immediately following the mol***es bath.
Skim coat of Rage to fill the pits then block sand.
2k urethane primer over that.
Done.

 

This "fix" was over 10 years old. Hasn't changed since it was done. I did cut out and replaced some of the window frame farther forward of this, but this area was touched up with filler, primed and painted again.
This area was first sanded as smooth as possible, then was covered by two rounds of Ospho (as per directions), then 2 coats of primmer (as per instructions) followed by filler, primmer, and paint. Ospho is a rust converter and I have used it for years on pitted metal with these same results.

 

This is what I use. You get 32oz of rust gel for $12, where as evoporust and naval jelly is $8 for 8oz. Being a Gel it works good on vertical surfaces. After I strip and disk the surface I use the rust remover to get out the pitted rust. Let it sit for a day and s****e with a putty knife, then wash off with soap water. might take a couple applications. I follow after with the metal prep phosphoric acid which is a gallon for $18 or so bucks. Wash again, sand with 80 grit, wax grease remover then epoxy prime.

 

I use the concrete prep too.I keep the work area wet for several hours until it turns gray,or black.Then I rinse,and blow dry any seam. I use a primer called rust destroyer that you can get at paint stores,or better hardware stores. Rust doesnt return.