Like 66 sprint said there are different levels. While the DuPont/PPG/Spies Heckler......ect. professional ones are top tier there are some better spray can primers available at paint suppliers. I bought some that was epoxy based (not laquer) when I touched up my engine compartment when doing panel replacement and repairs. It was $16 a can but sprayed real nice for a spray can and took 24 hrs to fully dry before being top coated. I don't remember the name of it though. I top coated it with Plasti-coat T-8 Satin Black in the engine compartment.
I would stay away from anything laquer based for being put under a paint job you want to last a long while. Also decide what paint you will be using as a finish and that it is compatible to what you are using as a primer and/or sealer. Keep in mind that unless it is an epoxy that the primer will actually ABSORB water (rain, dew, ect) and will cause the metal underneath to rust if not topcoated.
(Now that I have bought a set of LVLP guns I'll be stepping up to the better paints now that I can spray them. They (and HVLP) were out of my budget years ago as I needed other tools more pressingly and had to chose where to spend my money
For protected areas, engine compartment, the spray can stuff holds up well on a non-everyday driver.)
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1968 Mustang coupe, Acapulco Blue, 289 2v, C-4, Power Steering.
Hopefully a 1969 convertible or Sportsroof (non Mach or Boss) for next Mustang project
Trying to find my father's 1973 Mustang Grande he bought brand new. 3F04F126773 last known registration and title was in New Jersey, 1982.
Spray can Primer? 
