Can I apply Danish or teak oil on a pressure timber?

I don't see why not, but don't expect it to look all that great. Pressure treated wood is usually (in fact almost always) used in exterior applications, like fences, decks and sheds. There are specialized top coats you can put on them to help protect them from the elements like Thompson's Water Seal. read more

I would also recommend Teak Oil, as Danish oil is primarily for indoor use (but can be used outdoors). Note the Description on the Amazon page for Watco Teak Oil. “Although I do like teak oil as a finish for exterior wood, it's not usually recommended for decks. Foot traffic is the reason why. read more

Apply Danish and Teak oil with a soft brush or cloth, being careful not to use too much at a time or it won’t sink in. Sand the wood in between coats with a fine sandpaper. You will probably find 3 or 4 coats of oil is your optimum, delivering the best results. read more