What year? My 92 has brakes just like nearly all other production disk types. I've done my front brakes 3 times, and last time replaced flex hose with after market stainless protected hoses. Need one on each side. Otherwise, I think std OEM hose replacement should be OK. Your friend should find his experience can be safely used on BMWs. Do be careful not to cross thread hard and flex hoses. Also I suggest you use flare nut wrench on fittings. These are not very expensive, and available at most parts stores. If you do replace hoses, you must bleed brake lines. Nothing tricky here if use two person technique. Ask friend. Sequence FR then FL, if only front axel replacement.