Thanks for all the options and advice, guys.

I have used POR-15 for my Mini's fuel tank, and yes it does stick well to other materials, including concrete.
I will have to wait to do this project - still too cool and wet out to think about painting anything.

I use a product called Ospho which essentially stops/slows the oxidation process and turns sanded bare metal into a blackish colour ready for paint.

I have never used it on non sanded areas though but i have left the product on bare metal actually on a Mini floor for over a year and it still looks the same, not pretty but halted the metal eating process until i can get to the floor to finish it.

POR15 is probably better but brush on Rustoleum iron oxide primer followed with Rustolium brush on paint holds up well over rusty surfaces. The spray on version does not work.

Unless their formulation has changed, it is not that POR won't last as long in the sun, it's that the POR color will be affected by the light.  POR has traditionally been available in only three colors:  black, grey, and silver.  If you want to paint over it with a color top coat... that takes even more planning and prep.

KBS same as POR15 but the KBS has a UV protector in it, they both do the same job, but POR15 in the sun will not last as long. you can buy the KBS in different colors also

POR-15 can work very well and last a long time holding off rust, if you keep in mind how it works - by sealing off rust from further contact with oxygen and moisture.

That means if you just paint over visible rust, it will still probably fail in a few months to a year depending on exposure to the elements. You have to seal every path moisture has to the corrosion. There are two main ways where POR-15 usage is compromised:

1) not addressing the backside of the metal - so the corrosion just keeps going on the other side and eventually eats up the base that the POR-15 is bound to 

2) Not exposing all the rust so it can be sealed with POR-15. If you just coat the visible rust, even after scraping away the flakes, it usually isn't enough. The rust is like a growing cancer underneath apparently shiny paint, and if that rust isn't sealed, then moisture will still penetrate the existing paint above it and keep growing.

You need to grind off the apparently intact paint around the rust spots too until all of it is exposed. Then you can seal it effectively with POR-15.

por-15 Dan,,,Doug had it right.  It gets doggone hard. My ~10 yr old snowblower is starting to get a little rough around the edges, and that's what I'll eventually hit it with.

If you can at least chip off the worst loose material, you could follow up with POR-15.  I believe they still offer sample/starter kits to introduce you to their product and process.  One of those should do be capable of coating more than a single snow blower.  Keep it off your skin or you will wear it for days.

EDIT:  POR sample kit link below.
https://www.por15.com/POR-15-Stop-Rust-Kit
and Canadian ordering link below.
https://por15canada.com/

I've used a rust reformer product that you spray on. It sprays on milky white , then turns to black. It will last a couple months  to a year, then it will flake off in large chunks. The rust underneath the spray really never stops. It's a band aid. Covers everything up for a while allowing it to fester.

If you are able.  Scrape off the large chunks, wipe clean and then paint over everything with an oil based paint. 

OKAY... it is my snowblower, not my Mini.

The shell/body of my snowblower has what appears to be a baked-on enamel finish... which is peeling off in small sheets.
The underlying steel is lightly rusted, not flaking and not perforated. Due to health, I can't do extensive scraping and wire brushing to take it all back to bare metal.

I have read on here about some form of spray coating that "restores" rust. Any product suggestions? Or should I go with a Tremclad type paint?