I've used candle scents {fluids used for scenting home made candles} and they also worked very well for me.
I also use Mineral Oil, but may mix in a small amount of candle scent fluid or even a small amount of perfume, only about 25ml to a standard small glass bottle{same size that regular smoke fluid comes in} of mineral oil {90% bottle filled with mineral oil + 25ml of perfume}, this has also worked very well and kept the smoke unit clean due to the perfume having a wee bit of alcohol in it.
Never use full perfume or you could possibly start a fire in the smoke unit and your loco may go up in smoke!
I've found this mixture of mineral oil{90% filled smoke bottle} + regular perfume{25ml} to work very well, give a pleasant smell and after experimenting with it for over 6+ months, no detrimental effects to the loco or smoke system.
NOTE: if using this method, always shake the fluid bottle vigoursly to keep everything mixed well before putting it into your smoke unit!
