4.9L - if you want to go ultra cheap, a $10 bottle of "ospho" from your local Ace Hardware (or equivilent) will do your frame just nicely. It was enough to coat my crewcab frame twice...

The only rust you really have to remove is the flaky loose stuff. Surface rust you can leave. Which means a metal paint scraper, a screwdriver for poking, and a wirewheel can do the job good enough for ospho.

I sandblasted my frame, must because I had the truck apart enough that I could get the sand to hit everywhere...

Before and after pictures.

First: frame after the bed came off. Surface rusted to hell.
Second: Frame after ospho applied in two coats.
Third: frame snout after taking radiator support off. Yuck,
Fourth: same frame snout after repairing broken ear, application of ospho in two coats, prime and paint with rustoleum industrial black. It's almost as smooth as glass. Ignore the bubbly looking surface, that's my camera flash exhaggerating the water droplets. It rained for two days after I painted the frame.

Tell me that's not purty!

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