POR-15

[Daniel Neuman <dneuman@stars.sfsu.edu>]

Hello ALl,
        I will be doing some cleaning up on the underside of my car and I was
wondering how much will a quart of POR-15 cover?? I am planning on doing the
rear diff-leafsprings-wheel wells, the engine bay and the block.. Is this 
going to be enough??  
        Is it absolutely needed to use the POR-15 pre treatment on rusty metal?

                Thanks,
                        Daniel 69 2000