Non detergent oil is just that, oil without detergent. The theory is if you have an old engine with sludge build up, the detergent will loosen it up and allow it to clog your oil passages. As far as the brake lines go, yes, just swap them. It's an easy job. I like to hit all of the connections with PB blaster or wd a day or two before attempting to change old lines that have been sitting. Helps save the hassle of stripped fittings. A set of line wrenches helps too. And lastly, Marvel mystery oil is still going strong, haha.