Best primer for over grime

[The Rusty Gear]

My "new to me garage" was probably painted in the 70's and looks pretty bad. I know it's just a garage and not a showroom, but I thought before I move the stuff in I should give it a fresh coat of paint to brighten the place up. Is there a good primer that I can use so I don't have to wash the walls first? They don't look too bad and no visible grease, mostly faded and some spots I can tell they did just one coat and I can see the drywall and mud lines. Could I just roll paint on over existing if I get a "good" paint?

 

[RPH]

Wash with TSP and rinse with water. Should be able to spray the TSP on watch the dirt disappear, at most brush with broom. Rinse with the hose. Prime with your choice. Painting over the grime will not let the new material adhere well. It will fail in the future.

 

[Richard Givan]

If you have places with visible stains, you might put on a coat of Kilz primer. It has a great rep for sealing in those nasty little stains that have a way of seeping out in the future to ruin your nice new paint job.

 

[trackwelder]

Zinsser brand BIN primer.