When i pee it sometimes feels slimy or oily, even during when i poop it happens, why is that? is it to do with my diet or mucus?

It's not clear what you mean. Are you referring to mucus or white fluid from your penis during bowel movements? This occurs normally from time to time, due to stool passing over the prostate gland and seminal vesicles. If no mucus or other discharge at other times and no pain on urination, probably nothing is wrong. But see a doctor (e.g. a urologist) if it continues or you remain concerned.