A bit of oil vapour in silicon hose isn't too much a problem - carrying pressurised oil/fuel constantly is totally different and will make the hose break down that much quicker so I suppose you could use normal silicon hoses and change them every few days but it just stands to reason that its safer to use silicon hoses that are designed to carry fuel/oil. As I said before oil and fuel will break down standard silicon hoses that aren't designed to carry oil/fuel. There are all types of silicon hoses, oil, fuel, boost, coolant, vacuum and normal bog standard single layer non-reinforced. You also get straights, flexi and superflexi, different hose for a different application.