Asking partners, while not perfect is a good idea an will reduce your risk
somewhat. As for oral sex, the quoted figure for HIV risk
, if one has oral sex with an infected partner is less than 1 in 10,000 and, in my estimation that is far too high. Some experts state there is no risk at all from oral sex. Neither of us on this site have ever seen or reading the medical literature of a convincing instance in which HIV was passed by oral sex.