from the R&F website: "All of our inks are opaque and waterproof so the colour of the design is not affected by the colour of the surface which the decal is applied to".

However it doesn't say it's oil proof.

I'd imagine they are laser inks, not inkjet, as I'm pretty sure you'd only get metallics from a laser printer metallic colours. I'm also assuming that the outline on your Fender-style font is silver.