What's the clear liquid/oil that comes out of pimples? is it the same as pus?

Yes: Pus may be thick or thin, opaque or clear.

Serum: If it is clear it is more likely to be liquid part of blood, i.e., serum. Do not pop the pimples. You may consult this site for home treatment for pimples/acne. http://www.webmd.com/skin-problems-and-treatments/acne/acne-vulgaris-home-treatment

Interstitial fluid: All cells are bathed with interstitial fluid, which then drains into the lymphatics. This fluid is clear and resembles plasma & is the fluid that in "water blisters" or burns. Pimples are infected hair follicles and the fluid is usually yellow or milky, and that is pus, a mixture of tissue fluid, white blood cells and sebum or oil. Normal hair follicles secrete sebum, which is a clear oil.