Hi to everyone, I wanna know how can I improve my pale ale´s head retention, for example if I had to use oats, it need to be mashed the same time as base malt?
Hi,
 I personally would not use oats in a pale ale - it would add a large amount of chill haze that would be very hard to get rid of.
 I usually include 0.5 to 1lb of crystal or caramel malt and 4 to 8 oz of carafoam (also called carapils) malt.  Both will improve your head retention without adding excessive haze.
A quarter pound of flaked barley won't add much to the beer except good head retention. Wheat malt will do the same thing. And really, truth be told, you won't notice a lot of extra body from a quarter or half pound of carapils/carafoam/detrine malt.
Again, if you are going for a pale ale I would recommend Carapils instead of flaked barley (clarity issues due to protein haze from the flaked barley).
I would probably add no more than about 1/2 lb of either to a 5 gal batch for head retention.