I need to know what coatings are grease proof and good for outdoor applications, e.g. CV axles.
I want to sandblast or wire brush old Cv axles and coat them with something. I have considered powder coating but it is unclear if the epoxy will stand up to the elements or if polyester will resist the grease. Also unclear if POR products fit the bill. I suppose they could be plated but I don’t want to manipulate the spline area. If I find shrink tubing large enough I could get that too because it should stand up well. What about mixing the 5-min epoxy and spreading it on the rusty axle as-is?
Last time I rebuilt a CV joint, I wirebrushed the axle clean, primed it with Rustoleum primer, and painted them yellow with a gloss yellow Rustoleum rattle can. The CV boots were red silicon, so the contrasting colors worked great.
Have you considered using epoxy-based paint?
Truth is, axle coatings are not subjected to mechanical or thermal stresses. If they’re properly cleaned, and primed, any spray on paint will work well.
And, yeah, be sure to protect the splines.
Yellow & red? Hmmmmmm… 
It was an air-cooled V-Dub Type 3 Fastback. I was a teenager at the time. And the splines were masked off. I only painted just past the notch for the boot seat. Looked good for a long time.