I think I would re-sand your car with 400 before you paint it. My experience with Rust-oleum is it won't like to stick to a finer sanded base. Even thinned, the Rust-oleum is thick paint designed to cover voids well. There would have to be very deep scratches to show through it.

I don't know about the Rust-oleum acrylic, but spraying the standard Rust-oleum says re coat before 4 hours or after 48 hours. Its a pretty thin line between being ready to accept that next coat, and running the next coat. I suggest you start the 2nd (and later) coats in an area where a small run won't kill you (it will be weeks before you can fix the run). I would think the base and the clear coat would be applied the same way, if it doesn't tell you differently on the cans. I would do a minimum of 2 coats of each, depending on your coverage, 3 might be best. With the oil base, you pretty much get done with the 1st coat and you start the 2nd coat. It gets to be a long day. You can't sand the oil base until at least a week later, and then its going to be very wet 400.

You may not need anything to thin it for spraying it, but you will need something for cleaning the gun afterwords. The Rust-oleum is a pita to clean out of the gun.

Please post your results, I've got a truck I will be painting in a couple of months. Gene

If you are using a solid color, as a first time home sprayer, you should just go with a basic single stage (catalyzed) urethane such as Kirker. You don't need a base/clear for a solid color.

I bought Kirker ultra glo urethane "fleet white" via autobodytoolmart, link below. I'm sure you could get the paint and hardener, and reducer, for under 200. I bought two 3/4 gallon containers for my 68 satellite, and have leftover (don't remember how much unfortunately). I was one of the guys who rolled paint on my Dart a long time ago-- I used Topside boat paint, so at least it was shinier, but was bummed at the softness of it.

I was also a first time sprayer with Kirker, and it went well for a first time. Yes I have to do some wetsanding, but I expected to, and it's not the paints fault, so no biggie. It's rock hard within a few hours. I even used some just thinned, no hardener, to paint the trunk jamb and even without catalyst it dried super hard.

If you can still return that rustoleum, I certainly would. That non catalyzed paint is not going to shine or resist scratches like a 2 part paint, the two parts being paint and catalyst.


https://www.autobodytoolmart.com/ultra-glo-acrylic-urethane-enamel-paints-c-1453.aspx

Automotive paint is meant to be sanded but only after application. Base coat should not be sanded and should require only one to two coats. Clear should be applied in multiple coats 2-4 based on your plans to cut and buff.

400 grit scratches will not show through and help the paint adhere to the surface. Once the clear is cured, and in the case of Rustolium paint it will take weeks if not months, you can wet sand. Start with 800-1000 grit and go up from there. Then you can start the buffing process.

Now, with all that said. You can wind up with a much better paint job that will last much longer and look better by using s simple single stage black from any of the mentioned suppliers, Kirker, Omni, or Nason. These will be proper automotive catalyzed paints that will cure enough to cut and buff in hours compared to weeks. Without the additional cost of a clear coat your total material cost should be in the ballpark of what you're planning to spend now.

Remember, painting is 90% preparation and 10% actual painting. Sand the surface properly and use the best quality product you can afford and you won't be sorry. Also, modern automotive paints are a miracle of chemistry. They are designed to be compatible within a paint line and may not work at all when mixing brands, ie: spraying a different brand of clear over a base. If you try that any number of things can happen including the paint balling up and looking like wrinkle paint. That's why everyone is telling you to try it on something other than your car before you use it.

Bottom line... use a real automotive catalyzed single stage and you will be much happier with the outcome. The "P" sheets will tell you what sanding surface it needs, and what pressure to spray, as well as everything else you need to know to successfully spray the paint. If a paint does not have a "P" (Product) sheet, it isn't really "automotive" grade paint. Might be something you would paint your tractor with, but not a car.

The truck below was painted with a catalyzed single stage Omni brand automotive paint with no clear coat. Cost was about $250 total.



The '41 Chevy below was painted with base/clear. Total cost of materials, $1800.



Not that much difference except the cost of materials. Unless you're going to do a "show" paint job you really don't need to use a two stage (BC/CC) paint.

Good luck.