No you do not. No oil, nothing at all. In my view it is the safest and most efficient way of dealing with ear wax. I suspect Squad will disagree, but one of the consultant ENT specialists I saw a few years ago told me never ever to put oil in my ears because if I had an infection that would be a bad thing to do. I did question this advice because GPs and nurses all recommend this, but he was adamant I shouldn't do it. So I don't. I guess if you don't have an infection it won't do any harm and will soften the wax, but with the vacuum method you do not need any prior preparation at all.