Every year surface rust shows up in spots on the frame beneath the doors and on the edges of the skid plates. Every year I abrade it and hit it with flat-black. Even tried paint with built-in primer. Any thoughts about spraying over the areas with a rubberized material such as Plasti Dip, Monstaliner…or even Flex Seal to keep it from reoccurring. Obviously won’t be using a rubberized product on the exposed side of the plates...thanks!

 

I use rustoleum rust inhibitor primer before I hit it again with semi-gloss black. Been working great for me. The underside of my jeep still looks new. I just give it quick touch ups every 6 or so months. I've had my current jeep for 2.5 years now and I live in Massachusetts. We see rust out here, a lot!

 

I used flat black truck bed-liner spray from a rattle can last summer on all my wheel wells, some of the frame and the metal strip directly behind the grill that likes to rust and look bad. This spring everything still looks good after a Michigan winter of salty roads. I'm going back to hit the parts I missed last summer like the skid plates and the additional areas of the frame and axles. So far so good.

 

I would recommend a rustoleum paint, and keep doing what you are. I do the same, once a year scrub, then lay on my back and rattle can the frame with semi gloss black rustoleum.

I would stay away from any rubberized material, as I learned the hard and sad way, it hides any corrosion which develops under the coating, as it does not seal it 100%, and traps moisture underneath. You can not simply sand it off, as you do now with just paint, as it makes a sticky mess!

Trust me, my frame off 1983 CJ-7 has been reduced to a pile of rust AGAIN!
Especially on the floor board seams, it literally ate through from the inside out!

Keep spraying it once a year, that way you can see what is going on, and you may also see any maintenance your jeep may need when you are starring at its underside!

 

I've been using VHT Chassis and Suspension Epoxy for a number of years on various trucks. It looks almost identical to your jeeps factory black frame, and covers well. If parts are removed, I'll POR15 the part, and then top coat with a couple layers of the VHT. I also like that VHT is at Advance Auto and Autozone, so I can stop and grab a few cans on the way home from work if I am low. I always stock 2-3 cans of this stuff.

 

because i never had this issue with any vehicle ive ever owned untill it had over 100,000 miles on it . with my 2 jeeps i bought in recent past both required the purchase of semi flat blk paint from the day i picked them up . my rubicon even came from factory with rust under it and that just came off assembly line and was transported to me . Very odd to me . All i can attribute this to is cheap china steel
AS everyone has learned here on this issue it requires lots of rattle can use to keep it from turning into a rust bucket within a year or two . A lot of talk on using por 15 and things that will require way to much effort and rather toxic as well .
What really should be done is have Chrysler address the issue at the factory to end all .

till then, Its rustoleum semi gloss products that they must have shares in.