ehrm yes and no . the systems for automotive use and high flow aplications basicly all capable of drawing the feul in liquid form the pickup for automotive aplications is below the fluid level in carpropane tanks , thats basicly the reason why you shouldnt use a cars standard pickup point on the tank to light up the barbi , it would allso light the house and the person lighting it along wth the meat as the unlit barbi in the worst case will become a birdbath filled with liquid propane filling up to the edge and rolling over it as a vapor (depending on outside temperature ) can you say big boomn and smokehood entering the atmosfere ?
the evaporator / vaporizer in car applications im talking about is extremely simply put a box split intoo two hallways in one hallway they route the engine coolant , and through the other hallway the semi liquid propane (the propane does vaporize some on route to the vaporizer depending on the temperature of the outside air) the heat from the engine cooland helps the liquid turn intoo gas at the rate needed for the cars engine thats why theres a small copper line from the tank to the vaporizer and a larger line from the vaporizer to the cars intake , the explanation is extremely simple in the real evaporizers theres also a filtration section with some metal wool , and a membrane that works like a vacuumoperated valve the engine draws too mush propane to be able to transport it in gasform from the tank
the smaller setups i was talking about for generators and lawnmowers do draw the gas from the top of the tank so they shouldnt have as mush problems with the oily stuff like you mentioned